National Collaborating Centre forWomen’s and Children’s Health

Antenatal careroutine care for thehealthy pregnant woman

Clinical GuidelineMarch 2008Funded to produce guidelines for the NHS by NICE

RCOGPress2008

RCOG Press

Published by the Royal College ofObstetricians and Gynaecologists. To purchase further copies and for

a complete list of RCOG Press titles, visit: www.rcogbookshop.com

Antenatal care

Antenatal careroutine care for thehealthy pregnant woman

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Other NICE guidelines produced by the National Collaborating Centre forWomen’s and Children’s Health include:

• Fertility: assessment and treatment for people with fertility problems• Caesarean section• Type 1 diabetes: diagnosis and management of type 1 diabetes in children

and young people• Long-acting reversible contraception: the effective and appropriate use of

long-acting reversible contraception• Urinary incontinence: the management of urinary incontinence in women• Heavy menstrual bleeding• Feverish illness in children: assessment and initial management in children

younger than 5 years• Urinary tract infection in children: diagnosis, treatment and long-term

management• Intrapartum care: care of healthy women and their babies during childbirth• Atopic eczema in children: management of atopic eczema in children from

birth up to the age of 12 years• Surgical management of otitis media with effusion in children• Diabetes in pregnancy: management of diabetes and its complications from

preconception to the postnatal period

Guidelines in production include:• Induction of labour (update)• Surgical site infection• Diarrhoea and vomiting in children under 5• When to suspect child maltreatment• Meningitis and meningococcal disease in children• Neonatal jaundice• Idiopathic constipation in children • Hypertension in pregnancy• Socially complex pregnancies • Autism in children and adolescents

Enquiries regarding the above guidelines can be addressed to:

National Collaborating Centre for Women’s and Children’s HealthKing’s CourtFourth Floor2–16 Goodge StreetLondonW1T 2QAenquiries@ncc-wch.org.uk

A version of this guideline for pregnant women, their partners and the public is available from theNICE website (www.nice.org.uk/CG062) or from NICE publications on 0845 003 7783; quotereference number N1483.

Antenatal careroutine care for the healthy pregnant woman

National Collaborating Centre for Women’sand Children’s Health

Commissioned by the National Institute for Health and Clinical Excellence

March 2008

This is a partial update of the 2003 guideline. New or amended sections are indicated by a grey bar in the margin.

RCOG Press

Published by the RCOG Press at the Royal College of Obstetricians and Gynaecologists, 27 Sussex Place, Regent’s Park, London NW1 4RG

www.rcog.org.uk

Registered charity no. 213280

First published 2008, revised reprint 2008 (page 98)

2nd edition © 2008 National Collaborating Centre for Women’s and Children’s Health1st edition published in 2003

No part of this publication may be reproduced, stored or transmitted in any form or by any means, without the prior written permission of the publisher or, in the case of reprographic reproduction, in accordance with the terms of licences issued by the Copyright Licensing Agency in the UK [www.cla.co.uk]. Enquiries concerning reproduction outside the terms stated here should be sent to the publisher at the UK address printed on this page.

The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore for general use.

While every effort has been made to ensure the accuracy of the information contained within this publication, the publisher can give no guarantee for information about drug dosage and application thereof contained in this book. In every individual case the respective user must check current indications and accuracy by consulting other pharmaceutical literature and following the guidelines laid down by the manufacturers of specific products and the relevant authorities in the country in which they are practising.

ISBN 978-1-904752-46-2

NCC-WCH Editor: Andrew WelshOriginal design: FiSH Books, LondonTypesetting: Andrew WelshProofreading: Katharine Timberlake (Reedmace Editing)Index: Jan Ross (Merrall-Ross (Wales) Ltd)Printed by Henry Ling Ltd, The Dorset Press, Dorchester DT1 1HD

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Contents

Guideline Development Group membership and acknowledgements viOriginal (2003) version:Guideline Development Group viAcknowledgments viStakeholder organisations viPeer reviewers vii2008 update:Guideline Development Group viiiAcknowledgments viiiStakeholder organisations viiiAbbreviations xiiGlossary of terms xvi1 Introduction 11.0 Introduction 11.1 Aim of the guideline 11.2 Areas outside the remit of the guideline 21.3 For whom is the guideline intended? 31.4 Who has developed the guideline? 31.5 Who has developed the guideline update? 31.6 Guideline methodology 42 Summary of recommendations and care pathway 122.1 Key priorities for implementation (key recommendations) 122.2 Summary of recommendations 132.3 Key priorities for research 252.4 Additional research recommendations 262.5 Care pathway 273 Woman-centred care and informed decision making 373.1 Introduction 373.2 Provision of information 373.3 Antenatal classes 584 Provision and organisation of care 674.1 Who provides care? 674.2 Continuity of care 674.3 Where should antenatal appointments take place? 694.4 Documentation of care 694.5 Frequency of antenatal appointments 704.6 Gestational age assessment 734.7 What should happen at antenatal appointments? 785 Lifestyle considerations 825.1 Physiological, psychosocial and emotional changes in pregnancy 825.2 Maternity health benefits 825.3 Working during pregnancy 825.4 Dietary information and education 835.5 Nutritional supplements 845.6 Food-acquired infections 925.7 Prescribed medicines 935.8 Over-the-counter medicines 935.9 Complementary therapies 935.10 Exercise in pregnancy 945.11 Sexual intercourse in pregnancy 955.12 Alcohol and smoking in pregnancy 955.13 Cannabis use in pregnancy 1015.14 Air travel during pregnancy 1015.15 Car travel during pregnancy 1025.16 Travelling abroad during pregnancy 103

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6 Management of common symptoms of pregnancy 1066.1 Nausea and vomiting in early pregnancy 1066.2 Heartburn 1086.3 Constipation 1096.4 Haemorrhoids 1106.5 Varicose veins 1106.6 Vaginal discharge 1116.7 Backache 1126.8 Symphysis pubis dysfunction 1136.9 Carpal tunnel syndrome 1137 Clinical examination of pregnant women 1147.1 Measurement of weight and body mass index 1147.2 Breast examination 1157.3 Pelvic examination 1157.4 Female genital mutilation 1167.5 Domestic violence 1177.6 Psychiatric screening 1188 Screening for haematological problems 1208.1 Anaemia 1208.2 Blood grouping and red cell alloantibodies 1218.3 Screening for haemoglobinopathies (sickle cell disease and thalassaemia) 1229 Screening for fetal anomalies 1349.1 Screening for structural anomalies 1349.2 Screening for Down’s syndrome 15410 Screening for infections 18010.1 Asymptomatic bacteriuria 18010.2 Asymptomatic bacterial vaginosis 18310.3 Chlamydia trachomatis 18410.4 Cytomegalovirus 19310.5 Hepatitis B virus 19410.6 Hepatitis C virus 19410.7 HIV 19510.8 Rubella 19710.9 Streptococcus group B 19810.10 Syphilis 20010.11 Toxoplasmosis 20211 Screening for clinical problems 20511.1 Gestational diabetes 20511.2 Pre-eclampsia 21811.3 Preterm birth 22811.4 Placenta praevia 25112 Fetal growth and wellbeing 25312.1 Introduction and background 25312.2 Diagnostic value for predicting SGA babies 25512.3 Diagnostic value for predicting LGA babies 26512.4 Effectiveness studies 26712.5 Health economics evidence 27412.6 Fetal wellbeing 27513 Management of specific clinical conditions 27813.1 Pregnancy after 41 weeks 27813.2 Pregnancy after 42 weeks 27913.3 Breech presentation at term 28014 Antenatal assessment tool 28214.1 Introduction and background 28214.2 Systematic review of the evidence 28214.3 Developing an antenatal assessment tool 286Appendix A Declarations of interest 290Appendix B Economic model: asymptomatic bacteriuria screening programme 292Appendix C Economic model: streptococcus group B screening programme 294Appendix D Economic model: syphilis screening programme 295

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Appendix E Economic model: screening for congenital cardiac malformations 297Appendix F Economic model: screening and treatment of gestational diabetes 305Appendix G Economic model: monitoring fetal growth 331Appendix H Training and equipment standards for ultrasound screening in pregnancy 336Appendix I Further information 337Appendix J Family origin questionnaire 338Appendix K Deleted material from the 2003 version 3392.1 Summary of recommendations 3392.3 Algorithm – Antenatal care: routine care for the healthy pregnant woman 3413.1 Provision of information 3443.2 Antenatal education 3454.6 Gestational age assessment: LMP and ultrasound 3475.5 Nutritional supplements 3485.12 Alcohol and smoking in pregnancy 3488.2 Screening for sickle cell disorders and thalassaemia 3499 Screening for fetal anomalies 3509.1 Screening for structural anomalies 3519.2 Screening for Down’s syndrome 35310.1 Asymptomatic bacteriuria 35710.3 Chlamydia trachomatis 35711.1 Gestational diabetes mellitus 35811.2 Pre-eclampsia 36111.3 Preterm birth 36411.4 Placenta praevia 36512.2 Measurement of symphysis–fundal distance 36512.7 Umbilical and uterine artery Doppler ultrasound 36615 Auditable standards 368Appendix 1 369References (2003 version) 380References (2008 update) 397Index 408Search strategies CD-ROMExcluded studies CD-ROMEvidence tables CD-ROM

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Guideline Development Group membership and acknowledgements

Original (2003) version

Guideline Development GroupPeter Brocklehurst Group LeaderBelinda Ackerman MidwifeBrian Cook General PractitionerJoanie Dimavicius ConsumerHelen Edwards RadiographerGill Gyte ConsumerShahid Husain NeonatologistGwyneth Lewis Confidential Enquiry into Maternal DeathsTim Overton ObstetricianGill Roberts RCOG Patient Information SpecialistStephen Robson ObstetricianJulia Sanders MidwifeAnne White General PractitionerJane Thomas Director NCC-WCHSue Lee Research Fellow NCC-WCHJennifer Gray Informatics Specialist NCC-WCHNatalie Terry Administrative support NCC-WCHHannah Rose Douglas Health Economist, London School of Hygiene and Tropical MedicineDimitra Lambrelli Health Economist London School of Hygiene and Tropical Medicine

AcknowledgmentsAdditional support was also received from:• David Asomani, Anna Burt, Heather Brown, Susan Davidson, Gregory Eliovson, Susan Murray and Alex

McNeil at the National Collaborating Centre for Women’s and Children’s Health.• Stravros Petrou at the National Perinatal Epidemiology Unit and Kirsten Duckitt at the John Radcliffe

Hospital, Oxford.• Members of the previous Antenatal Care Guideline Development Group: John Spencer (Chairman), J

Bradley, Jean Chapple, R Cranna, Marion Hall, Marcia Kelson, Catherine McCormack, Ralph Settatree, Lindsay Smith, L Turner, Martin Whittle, Julie Wray.

• The Patient Involvement Unit, whose glossary we have amended for use in this guideline.• The Three Centres Consensus Guidelines on Antenatal Care, Mercy Hospital for Women, Monash Medical

Centre (Southern Health) and The Royal Women’s Hospital (Women’s & Children’s Health), Melbourne 2001, whose work we benefited from in the development of this guideline.

Stakeholder organisationsAction on Pre-Eclampsia (APEC)Antenatal Results and ChoicesAssociation for Continence Advice (ACA)Association for Improvements in Maternity Services (AIMS)

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Association of Radical MidwivesAssociation of the British Pharmaceuticals Industry(ABPI)Aventis Pasteur MSDBrighton Healthcare NHS TrustBritish Association of Paediatric SurgeonsBritish Association of Perinatal MedicineBritish Dietetic AssociationBritish Maternal and Fetal Medicine SocietyBritish Medical AssociationBritish National FormularyBritish Psychological SocietyBUPAChartered Society of PhysiotherapyCIS’tersDepartment of HealthEvidence based Midwifery NetworkFaculty of Public Health MedicineGateshead Primary Care TrustGeneral Medical CouncilGroup B Strep SupportHealth Development AgencyHospital Infection SocietyIsabel Medical CharityMaternity AllianceMental Health FoundationMonmouthshire Local Health GroupNational Childbirth TrustNHS Quality Improvement ScotlandNottingham City HospitalObstetric Anaesthetists AssociationRoyal College of General PractitionersRoyal College of General Practitioners WalesRoyal College of MidwivesRoyal College of NursingRoyal College of Obstetricians and GynaecologistsRoyal College of Paediatrics and Child HealthRoyal College of PathologistsRoyal College of PsychiatristsRoyal College of RadiologistsRoyal Pharmaceutical Society of Great BritainRoyal Society of MedicineScottish Intercollegiate Guidelines Network (SIGN)Sickle Cell SocietySociety and College of RadiographersSTEPSSurvivors TrustTwins and Multiple Births Association (TAMBA)UK Coalition of People Living with HIV and AIDSUK National Screening CommitteeUK Pain SocietyUnited Kingdom Association of SonographersVictim SupportWelsh Assembly Government (formerly National Assembly for Wales)West Gloucestershire Primary Care TrustYoung Minds

Peer reviewersSusan Bewley, Leanne Bricker, Howard Cuckle, Andrew Dawson, Viv Dickinson, Grace Edwards, Jason Gardosi, Duncan Irons, Deirdre Murphy, Tim Reynolds, Jilly Rosser, Lindsay Smith, John Spencer, Pat Tookey, Derek Tuffnell, Gavin Young.

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Guideline Development Group

GDG members

Rhona Hughes Group LeaderJane Anderson Ultrasound RadiographerChris Barry General PractitionerMarie Benton Service User RepresentativeJennifer Elliott Service User RepresentativeNina Khazaezadeh Consultant Midwife and Supervisor of MidwivesRachel Knowles Medical Research Council Clinical Public Health Research FellowTim Overton Consultant ObstetricianKatie Yiannouzis Head of Midwifery

National Collaborating Centre for Women’s and Children’s Health (NCC-WCH) staff

Rupert Franklin Work-Programme CoordinatorEva Gautam-Aitken Work-Programme CoordinatorPaul Jacklin Senior Health EconomistRajesh Khanna Senior Research FellowRintaro Mori Research FellowFrancesco Moscone Health EconomistDebbie Pledge Senior Information ScientistJeff Round Health EconomistAnuradha Sekhri Research FellowRoz Ullman Senior Research FellowMartin Whittle Co-Director in Women’s Health

External advisers

Guy Rooney Genitourinary Medicine SpecialistAnne Longton Health VisitorFiona Ford DieticianJane Hawdon Consultant Neonataologist

Acknowledgments

Additional support was also received from:• Anna Bancsi, Angela Kraut, Moira Mugglestone and Martin Dougherty at the NCC-WCH• Allison Streetly, Programme Director for the NHS Sickle Cell and Thalassaemia Screening Programme.• Andrew Welsh, freelance guideline editor, whose editorial support was invaluable in the production of

this guideline.• Group Dynamics, who provided the voting equipment for the Assessment Tool consensus meeting.

Stakeholder organisations

Academic Division of Midwifery, University of NottinghamAction on Pre-EclampsiaAddenbrooke’s NHS TrustAll Wales Birth Centre GroupAntenatal Screening WalesAssociation for Psychoanalytic Psychotherapy in the NHSAssociation for Spina Bifida & Hydrocephalus (ASBAH)Association of Breastfeeding MothersAssociation of British Clinical DiabetologistsAssociation of Chartered Physiotherapists in Women’s Health

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Association of Medical MicrobiologistsAssociation of the British Pharmaceuticals Industry (ABPI)Baby LifelineBarnsley Acute TrustBarnsley PCTBDF Newlife (Birth Defects Foundation)Bedfont Scientific LtdBedfordshire PCTBerkshire Healthcare NHS TrustBirmingham Women’s Healthcare TrustBirth Trauma AssociationBradford & Airedale PCTBradford Teaching Hospitals NHS Foundation TrustBrighton & Sussex University Hospitals TrustBristol Health Services PlanBritish Association for Counselling and PsychotherapyBritish Dietetic AssociationBritish HIV Association (BHIVA)British Hypertension SocietyBritish Maternal and Fetal Medicine SocietyBritish National Formulary (BNF)British Psychological SocietyCalderdale PCTCASPECEMACHChartered Society of PhysiotherapyChelsea & Westminster NHS Foundation TrustChronic Conditions Collaborating CentreCIS’tersCO-AwarenessCommission for Social Care InspectionCommunity Practitioners and Health Visitors AssociationConnecting for HealthCotswold and Vale PCTCroydon PCTCytyc UK LtdDepartment of Health, Social Security and Public Safety of Northern IrelandDerbyshire Mental Health Services NHS TrustDet Norske Veritas – NHSLA SchemesDoula UKDown’s Syndrome AssociationDudley Group of Hospitals NHS TrustEnglish National Forum of LSA Midwifery OfficersEpsom & St Helier University Hospitals NHS TrustEvidence-based Midwifery NetworkFaculty of Family Planning and Reproductive Health CareFaculty of Public HealthFoundation for the Study of Infant DeathsGateshead PCTGloucestershire Acute TrustGloucestershire Hospitals NHS Foundation TrustGroup B Strep SupportGuy’s and St Thomas’ NHS Foundation TrustHealth Protection AgencyHealthcare CommissionHomerton University Hospital NHS Foundation TrustHuntleigh HealthcareKing’s College Hospital NHS Trust

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Liverpool PCTLiverpool Women’s Hospital NHS TrustLuton and Dunstable Hospital NHS TrustMast DiagnosticsMedicines and Healthcare products Regulatory Agency (MHRA)Mid and West Regional MSLCMilton Keynes PCTMonica Healthcare LtdMRC Centre of Epidemiology for Child HealthNational Childbirth TrustNational Chlamydia Screening ProgrammeNational Patient Safety AgencyNational Public Health Service – WalesNHS DirectNHS Health and Social Care Information CentreNHS Quality Improvement ScotlandNHS Sickle Cell and Thalassemia Screening ProgrammeNorth Tees and Hartlepool NHS TrustNorthwest London Hospitals NHS TrustNutrition SocietyObstetric Anaesthetists AssociationPartnerships for Children, Families, Women and MaternityPelvic PartnershipPERIGON (formerly the NHS Modernisation Agency)Phoenix PartnershipPNI ORG UKPositively WomenPost Natal Illness Organisation (PNI)Primary Care Pharmacists’ AssociationPRIMIS+Princess Alexandra Hospital NHS TrustQueen Mary’s Hospital NHS Trust (Sidcup)Regional Maternity Survey OfficeRegional Public Health Group – LondonRoyal College of General PractitionersRoyal College of MidwivesRoyal College of NursingRoyal College of Obstetricians and GynaecologistsRoyal College of Paediatrics and Child HealthRoyal College of PathologistsRoyal College of PsychiatristsRoyal College of RadiologistsRoyal Liverpool Children’s TrustRoyal Society of MedicineSalford Royal Hospitals NHS Foundation TrustSalisbury NHS Foundation TrustSandwell and West Birmingham NHS TrustSanofi Pasteur MSDScottish Executive Health DepartmentScottish Intercollegiate Guidelines Network (SIGN)Sefton PCTSheffield South West PCTSheffield Teaching Hospitals NHS TrustSickle Cell & Thalassaemia Association of CounsellorsSickle Cell SocietySociety and College of RadiographersSurvivors TrustTIPS Limited

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UK Coalition of People Living with HIV & AIDSUK Forum on Haemoglobin DisordersUK National Screening CommitteeUK Newborn Screening Programme CentreUK Thalassaemia SocietyUNICEF Baby Friendly InitiativeUnited Lincolnshire Hospitals NHS TrustUniversity College London Hospitals NHS Foundation TrustUniversity College London Hospitals NHS TrustUniversity Hospitals of LeicesterVictim SupportWelsh Assembly GovernmentWelsh Scientific Advisory Committee (WSAC)West Middlesex University Hospital NHS TrustWestern Cheshire PCTWiltshire PCTWirral University Hospital Teaching NHS TrustWomen’s Health Research GroupWorcestershire Acute NHS TrustWorthing and Southlands Hospital NHS TrustWorthing HospitalWyre Forest PCTYork NHS TrustYorkshire and Humber Local Supervisory Authority

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Abbreviations

AC abdominal circumferenceACHOIS Australian Carbohydrate Intolerance Study in Pregnant WomenACOG American College of Obstetricians and GynecologistsACTH adrenocorticotrophic hormoneADA American Diabetes AssociationAFG adequate fetal growthAFI amniotic fluid indexAFP alpha-fetoproteinAIDS acquired immune deficiency syndromeALPHA Antenatal Psychosocial Health AssessmentANC antenatal careAPEC Action on Pre-eclampsiaAPH antepartum haemorrhageASB asymptomatic bacteriuriaBD twice a dayBERR Department for Business, Enterprise and Regulatory ReformBMC bone mineral contentBMI body mass indexBP blood pressureBPD biparietal diameter or bronchopulmonary dysplasiaBV bacterial vaginosisBW birthweightCAMP Christie, Atkinson, Munch, Peterson testcBG120 min capillary blood glucose 120 minutes after glucose loadCDSC Communicable Disease Surveillance CentreCEGEN Confidential Enquiry into Counselling for Genetic DisorderscFBG capillary fasting blood glucoseCFGC customised fetal growth chartcfu/ml colony-forming units per millilitreCHO carbohydrateCI confidence intervalCINAHL Cumulative Index to Nursing and Allied Health LiteratureCMV cytomegalovirusCNS central nervous systemCOMA Committee on Medical Aspects of Food PolicyCPC choroid plexus cystCRL crown–rump lengthCRP C-reactive proteinCS caesarean sectionCTG cardiotocographyDA direct agglutination testDARE Database of Abstracts and Reviews of Effectivenessdf degrees of freedomDFA direct fluorescent antibody testDNA deoxyribonucleic acidDR detection rateDS Down’s syndromeDx DiagnosiseAg hepatitis e antigenEB elementary body

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ECV external cephalic versionEEA European Economic AreaEFW estimated fetal weightEIA enzyme immunoassayEL evidence levelELISA enzyme-linked immunosorbent assayEOGBS early-onset group B streptococcusEPDS Edinburgh Postnatal Depression ScaleEPIC external intermittent pneumatic compressionEU European UnionFBC full blood countFFN fetal fibronectinFGM female genital mutilationFGR fetal growth restrictionfl femtolitre (10−15 litres)FL femur lengthFPG fasting plasma glucoseFPR false positive rateFTA-abs fluorescent treponemal antibody – absorbed testGA gestational ageGBS group B streptococcusGCT glucose challenge testGD gestational diabetesGDG Guideline Development GroupGDM gestational diabetes mellitusGPP good practice pointGTT glucose tolerance testH/O history ofHADS Hospital Anxiety and Depression ScaleHb haemoglobinHBIG hepatitis B immune globulinHBsAg hepatitis B surface antigenHBV hepatitis B virusHC head circumferencehCG human chorionic gonadotrophin (can be total or free beta)β-hCG beta-human chorionic gonadotrophinHCV hepatitis C virusHDN haemolytic disease of the newbornHEED Health Economic Evaluations DatabaseHELLP haemolysis, elevated liver enzymes and low platelet countHIV human immunodeficiency virusHPA Health Protection AgencyHPLC high-performance liquid chromatographyHSI health sector initiativeHT hypertensionHTA Health Technology AssessmentICD-9 International Classification of Diseases, 9th editionICER incremental cost-effectiveness ratioIFG inadequate fetal growthIGT impaired glucose toleranceIL interleukinIM intramuscular(ly)IMDA interactive multimedia decision aidIPC intrapartum careIPV intimate partner violence IU international unitIUGR intrauterine growth restrictionLA latex agglutination test

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Abbreviations

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LBW low birthweightLCR ligase chain reactionLE leucocyte esteraseLGA large for gestational ageLMP last menstrual periodLR likelihood ratioLR− negative likelihood ratioLR+ positive likelihood ratioLSHTM London School of Hygiene & Tropical MedicineMCH mean corpuscular haemoglobinMCV mean corpuscular volumeMeSH medical subject headingsMIDIRS Midwives Information and Resource ServiceMMIC Multidimensional Measure of Informed ChoiceMoM multiples of the medianMOMP major outer membrane proteinMSAFP maternal serum alpha-fetoproteinMSHCG maternal serum beta-human chorionic gonadotrophinMSS maternal serum screeningMSU midstream urine sampleMTCT mother-to-child transmissionNCC-WCH National Collaborating Centre for Women’s and Children’s HealthNCRSP National Congenital Rubella Surveillance ProgrammeNEC necrotising enterocolitisNFG normal fetal growthNHS EED NHS Economic Evaluations DatabaseNHS National Health ServiceNICE National Institute for Health and Clinical ExcellenceNICU neonatal intensive care unitNNT number needed to treatNPI Neonatal Perception InventoryNPV negative predictive valueNS not significantNSC (UK) National Screening CommitteeNSF National Service FrameworkNT nuchal translucencyNTD neural tube defectOGTT oral glucose tolerance testOH oligohydramnios25-OHD 25-hydroxyvitamin DONS Office for National StatisticsOR odds ratioOTC over-the-counteroz fluid ounce (28.41 ml)PAI Prenatal Attachment InventoryPAPP-A pregnancy-associated plasma protein-APCR polymerase chain reactionPCT primary care trustPE pre-eclampsiapg picogram (10−12 grams)PHLS Public Health Laboratory ServicePI pulsatility indexPIH pregnancy-induced hypertensionPPV positive predictive valuePROM preterm rupture of the membranesPTD preterm deliveryQID four times a dayRBC red blood cell

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RBG random blood glucoseRCOG Royal College of Obstetricians and GynaecologistsRCT randomised controlled trialRhD rhesus DRIBA recombinant immunoblot assayRNA ribonucleic acidROC receiver operating characteristicROP retinopathy of prematurityRPG random plasma glucoseRPR rapid plasmin reagin testRR relative riskRST reagent strip testingS/D systolic/diastolicSACN Scientific Advisory Committee on NutritionSD standard deviationSE socio-economic(ally)SFH symphysis–fundal heightSGA small for gestational ageSIGN Scottish Intercollegiate Guidelines NetworkSP specificitySPD symphysis pubis dysfunctionSPTB spontaneous preterm birthST sensitivitySTAI Spielberger State-Trait Anxiety InventoryT 21/18/13 trisomy 21, 18 or 13TDS three times a dayTGA tranposition of the great arteriesTPHA Treponema pallidum haemagglutination assayTVS transvaginal sonographyuE3 unconjugated estriolUHT ultra-high-temperature processingUK United KingdomUS CDC United States Centers for Disease Control and PreventionUS ultrasoundUSPSTF US Preventive Services Task ForceUSS ultrasound scanUTI urinary tract infectionVDRL Venereal Disease Research Laboratory (test for syphilis)VE vaginal examinationWHO World Health OrganizationWMD weighted mean difference

Abbreviations

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Glossary of terms

Bias Influences on a study that can lead to invalid conclusions about a treatment or intervention. Bias in research can make a treatment look better or worse than it really is. Bias can even make it look as if the treatment works when it actually doesn’t. Bias can occur by chance or as a result of systematic errors in the design and execution of a study. Bias can occur at different stages in the research process, e.g. in the collection, analysis, interpretation, publication or review of research data.

Blinding or masking The practice of keeping the investigators or subjects of a study ignorant of the group to which a subject has been assigned. For example, a clinical trial in which the participating patients or their doctors are unaware of whether they (the patients) are taking the experimental drug or a placebo (dummy treatment). The purpose of ‘blinding’ or ‘masking’ is to protect against bias. See also double-blind study.

Body mass index (BMI) A person’s weight (in kilograms) divided by the square of their height (in metres). It is used as a measure of underweight, overweight or obesity.

Booking The appointment where the woman enters the maternity care pathway, characterised by information giving and detailed history-taking to help the woman choose the most appropriate antenatal care pathway. Also includes measurement of height, weight, blood pressure and blood tests for determining blood group, rubella status and haemoglobin level. Blood and urine samples for screening may also be taken at booking after the woman has been well informed and has given her consent. The booking appointment follows the first contact with a health professional.

Case–control study A study that starts with the identification of a group of individuals sharing the same characteristics (e.g. people with a particular disease) and a suitable comparison (control) group (e.g. people without the disease). All subjects are then assessed with respect to things that happened to them in the past, e.g. things that might be related to getting the disease under investigation. Such studies are also called retrospective as they look back in time from the outcome to the possible causes.

Case report (or case study) Detailed report on one patient (or case), usually covering the course of that person’s disease and their response to treatment.

Case series Description of several cases of a given disease, usually covering the course of the disease and the response to treatment. There is no comparison (control) group of patients.

Clinical effectiveness The extent to which a specific treatment or intervention, when used under usual conditions, has a beneficial effect on the course or outcome of a disease compared with no treatment or routine care.

Clinical question The term is sometimes used in guideline development to refer to the questions about treatment and care that are formulated in order to guide the search for research evidence.

Clinical trial A research study conducted with patients which tests out a drug or other intervention to assess its effectiveness and safety. Each trial is designed to answer scientific questions and to find better ways to treat individuals with a specific disease. This general term encompasses controlled clinical trials and randomised controlled trials.

Cluster A group of patients, rather than an individual, used as a basic unit for investigation. See also cluster randomisation.

Cluster randomisation A study in which groups of individuals (eg. attending one GP surgery) are randomly allocated to intervention groups. See also cluster.

Cohort A group of people sharing some common characteristic (e.g. patients with the same disease), followed up in a research study for a specified period of time.

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Cohort study An observational study that takes a group (cohort) of patients and follows their progress over time in order to measure outcomes such as disease or mortality rates and make comparisons according to the treatments or interventions that patients received. Thus within the study group, subgroups of patients are identified (from information collected about patients) and these groups are compared with respect to outcome, e.g. comparing mortality between one group that received a specific treatment and one group which did not (or between two groups that received different levels of treatment). Cohorts can be assembled in the present and followed into the future (a concurrent or prospective cohort study) or identified from past records and followed forward from that time up to the present (a historical or retrospective cohort study). Because patients are not randomly allocated to subgroups, these subgroups may be quite different in their characteristics and some adjustment must be made when analysing the results to ensure that the comparison between groups is as fair as possible.

Combined test A battery of screening tests used together to determine the risk of the unborn baby having Down’s Syndrome. The tests are: a nuchal translucency ultrasound scan plus blood tests to measure levels of a beta human chorionic gonadotrophin and pregnancy-associated plasma protein-A. The test should be performed between 11 weeks 0 days and 13 weeks 6 days.

Confidence interval A way of expressing certainty about the findings from a study or group of studies, using statistical techniques. A confidence interval describes a range of possible effects (of a treatment or intervention) that is consistent with the results of a study or group of studies. A wide confidence interval indicates a lack of certainty or precision about the true size of the clinical effect and is seen in studies with too few patients. Where confidence intervals are narrow they indicate more precise estimates of effects and a larger sample of patients studied. It is usual to interpret a ‘95%’ confidence interval as the range of effects within which we are 95% confident that the true effect lies.

Confounder or confounding variable/factor

Something that influences a study and can contribute to misleading findings if it is not understood and appropriately dealt with.

Consensus methods A variety of techniques that aim to reach an agreement on a particular issue. Formal consensus methods include Delphi or nominal group techniques, and consensus development conferences. In the development of a clinical guideline, consensus methods may be used where there is a lack of good research evidence.

Consistency The extent to which the conclusions of a collection of studies used to support a guideline recommendation are in agreement with each other. See also homogeneity.

Control group A group of patients recruited into a study that receives no treatment, a treatment of known effect, or a placebo (dummy treatment), in order to provide a comparison for a group receiving an experimental treatment, such as a new drug.

Controlled clinical trial (CCT)

A study testing a specific drug or other treatment involving two (or more) groups of patients with the same disease. One (the experimental group) receives the treatment that is being tested, and the other (the comparison or control group) receives an alternative treatment, a placebo (dummy treatment) or no treatment. The two groups are followed up to compare differences in outcomes to see how effective the experimental treatment was. A CCT where patients are randomly allocated to treatment and comparison groups is called a randomised controlled trial.

Cost–benefit analysis A type of economic evaluation where both costs and benefits of healthcare treatment are measured in the same monetary units. If benefits exceed costs, the evaluation would recommend providing the treatment.

Cost-effectiveness A type of economic evaluation that assesses the additional costs and benefits of doing something different. In cost-effectiveness analysis, the costs and benefits of different treatments are compared. When a new treatment is compared with current care, its additional costs divided by its additional benefits is called the cost-effectiveness ratio. Benefits are measured in natural units, for example, cost per additional heart attack prevented.

Cost–utility analysis A special form of cost-effectiveness analysis where benefit is measured in quality-adjusted life years (QALYs). A treatment is assessed in terms of its ability to extend or improve the quality of life.

Counselling For the purpose of the guideline, ‘counselling’ is defined broadly as supportive listening, advice giving and information. The British Association for Counselling and Psychotherapy offers a more specific definition of counselling as a discrete psychological intervention (regular planned meetings of usually 50 minutes in length) which is facilitative, non-directive and/or relationship focused, with the content of sessions largely determined by the service user’.

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Crossover study design A study comparing two or more interventions in which the participants, upon completion of the course of one treatment, are switched to another. For example, for a comparison of treatments A and B, half the participants are randomly allocated to receive them in the order A, B and half to receive them in the order B, A. A problem with this study design is that the effects of the first treatment may carry over into the period when the second is given. Therefore a crossover study should include an adequate ‘wash-out’ period, which means allowing sufficient time between stopping one treatment and starting another so that the first treatment has time to wash out of the patient’s system.

Cross-sectional study The observation of a defined set of people at a single point in time or time period – a snapshot. (This type of study contrasts with a longitudinal study, which follows a set of people over a period of time.)

Customised fetal growth chart

The customised fetal growth chart (CFGC) is the term used for an individually adjusted standard for fundal height, estimated fetal weight and birthweight which takes into consideration maternal characteristics such as height, country of family origin, cigarette smoking and presence of diabetes.

Delphi technique A technique used for the purpose of reaching an agreement on a particular issue, without the participants meeting or interacting directly. It involves sending participants a series of postal questionnaires asking them to record their views. After the first questionnaire, participants are asked to give further views in the light of the group feedback. The judgements of the participants are statistically aggregated. See also consensus methods.

Detection rate 100% minus sensitivity.

Diagnosis Confirmation of the presence of a disease/disorder.

Diagnostic study A study to assess the effectiveness of a test or measurement in terms of its ability to accurately detect or exclude a specific disease.

Double-blind study A study in which neither the subject (patient) nor the observer (investigator or clinician) is aware of which treatment or intervention the subject is receiving. The purpose of blinding is to protect against bias.

Evidence based The process of systematically finding, appraising and using research findings as the basis for clinical decisions.

Evidence-based clinical practice

Evidence-based clinical practice involves making decisions about the care of individual patients based on the best research evidence available rather than basing decisions on personal opinions or common practice (which may not always be evidence based). Evidence-based clinical practice therefore involves integrating individual clinical expertise and patient preferences with the best available evidence from research.

Evidence level (EL) A code (eg. 1++, 1+) linked to an individual study or systematic review indicating where it fits in the hierarchy of evidence and how well it has adhered to recognised research principles.

Evidence table A table summarising the results of a collection of studies which, taken together, represent the evidence supporting a particular recommendation or series of recommendations in a guideline.

Exclusion criteria See Selection criteria.

Experimental study A research study designed to test whether a treatment or intervention has an effect on the course or outcome of a condition or disease, where the conditions of testing are to some extent under the control of the investigator. Controlled clinical trials and randomised controlled trials are examples of experimental studies.

False positive rate 100% minus specificity.

First contact The initial appointment where the woman first meets a healthcare professional with a confirmed pregnancy. This appointment includes referral into the maternity care pathway and is an opportunity for information giving to ensure the woman is able to make informed decisions about her pregnancy care, including all antenatal screening and to raise awareness about health-related issues that are particularly relevant in early pregnancy.

Gold standard A method, procedure or measurement that is widely accepted as being the best available.

Gravid Pregnant.

Guideline A systematically developed tool that describes aspects of a person’s condition and the care to be given. A good guideline makes recommendations based on best research evidence available, rather than opinion. It is used to assist clinician and patient decision making about appropriate health care for specific conditions.

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Health economics A field of conventional economics which examines the benefits of healthcare interventions (e.g. medicines) compared with their financial costs.

Health technology Health technologies include medicines, medical devices, diagnostic techniques, surgical procedures, health promotion activities and other therapeutic interventions.

Heterogeneity Or lack of homogeneity. The term is used in meta-analyses and systematic reviews when the results or estimates of effects of treatment from separate studies seem to be very different, in terms of the size of treatment effects, or even to the extent that some indicate beneficial and others suggest adverse treatment effects. Such results may occur as a result of differences between studies in terms of the patient populations, outcome measures, definition of variables or duration of follow up.

Hierarchy of evidence An established hierarchy of study types, based on the degree of certainty that can be attributed to the conclusions that can be drawn from a well-conducted study. Well-conducted randomised controlled trials (RCTs) are at the top of this hierarchy.

Homogeneity This means that the results of studies included in a systematic review or meta-analysis are similar and there is no evidence of heterogeneity. Results are usually regarded as homogeneous when differences between studies could reasonably be expected to occur by chance. See also consistency.

Inclusion criteria See selection criteria.

Integrated test A battery of screening tests used together to determine the risk of the unborn baby having Down’s syndrome. The tests are: a nuchal translucency ultrasound scan plus blood tests to measure levels of a beta human chorionic gonadotrophin (β-hCG)and pregnancy-associated plasma protein-A. These tests should be performed between 11 weeks 0 days and 13 weeks 6 days. This is then followed by a second battery of blood tests: alpha-fetoprotein, uE3 and inhibin A between 15 weeks 0 days and 20 weeks 0 days. The woman waits for results from the second set of tests before she is told her risk level.

Intention-to-treat analysis An analysis of a clinical trial where particpants are analysed according to the group to which they are initially randomly allocated, regardless of whether or not they had dropped out of the study, fully received the intervention as intended or crossed over to an alternative intervention.

Intervention Healthcare action intended to benefit the patient, e.g. drug treatment, surgical procedure, psychological therapy.

Likelihood ratio See negative likelihood ratio and positive likelihood ratio.

Longitudinal study A study of the same group of people at more than one point in time. (This type of study contrasts with a cross-sectional study, which observes a defined set of people at a single point in time.)

Masking See blinding.

Meta-analysis Results from a collection of independent studies (investigating the same treatment) are pooled, using statistical techniques to synthesise their findings into a single estimate of a treatment effect. Where studies are not compatible, e.g. because of differences in the study populations or in the outcomes measured, it may be inappropriate or even misleading to statistically pool results in this way. See also systematic review and heterogeneity.

Multiparous Having carried more than one pregnancy to a viable stage.

Negative likelihood ratio (LR–)

The negative likelihood ratio describes the probability of having a negative test result in the diseased population compared with that of a non-diseased population and corresponds to the ratio of the false negative rate divided by the true negative rate ((1 – sensitivity)/specificity).

Negative predictive value (NPV)

The proportion of people with a negative test result who do not have the disease (where not having the disease is indicated by the gold test being negative).

Nominal group technique A technique used for the purpose of reaching an agreement on a particular issue. It uses a variety of postal and direct contact techniques, with individual judgements being aggregated statistically to derive the group judgement. See also consensus methods.

Non-experimental study A study based on subjects selected on the basis of their availability, with no attempt having been made to avoid problems of bias.

Nulliparous Having never given birth to a viable infant.

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Number needed to treat (NNT)

This measures the impact of a treatment or intervention. It states how many patients need to be treated with the treatment in question in order to prevent an event that would otherwise occur; e.g. if the NNT = 4, then four patients would have to be treated to prevent one bad outcome. The closer the NNT is to one, the better the treatment is. Analogous to the NNT is the number needed to harm (NNH), which is the number of patients that would need to receive a treatment to cause one additional adverse event. e.g. if the NNH = 4, then four patients would have to be treated for one bad outcome to occur.

Observational study In research about diseases or treatments, this refers to a study in which nature is allowed to take its course. Changes or differences in one characteristic (e.g. whether or not people received a specific treatment or intervention) are studied in relation to changes or differences in other(s) (e.g. whether or not they died), without the intervention of the investigator. There is a greater risk of selection bias than in experimental studies.

Odds ratio (OR) Odds are a way of representing probability, especially familiar from betting. In recent years odds ratios have become widely used in reports of clinical studies. They provide an estimate (usually with a confidence interval) for the effect of a treatment. Odds are used to convey the idea of ‘risk’ and an odds ratio of one between two treatment groups would imply that the risks of an adverse outcome were the same in each group. For rare events the odds ratio and the relative risk (which uses actual risks and not odds) will be very similar. See also relative risk, risk ratio.

Parous Having borne at least one viable offspring (usually more than 24 weeks of gestation).

Peer review Review of a study, service or recommendations by those with similar interests and expertise to the people who produced the study findings or recommendations. Peer reviewers can include professional, patient and carer representatives.

Pilot study A small-scale ‘test’ of the research instrument. For example, testing out (piloting) a new questionnaire with people who are similar to the population of the study, in order to highlight any problems or areas of concern, which can then be addressed before the full-scale study begins.

Placebo Placebos are fake or inactive treatments received by participants allocated to the control group in a clinical trial, which are indistinguishable from the active treatments being given in the experimental group. They are used so that participants are ignorant of their treatment allocation in order to be able to quantify the effect of the experimental treatment over and above any placebo effect due to receiving care or attention.

Placebo effect A beneficial (or adverse) effect produced by a placebo and not due to any property of the placebo itself.

Positive likelihood ratio (LR+)

The positive likelihood ratio describes the probability of having a positive test result in the diseased population compared with that of a non-diseased population and corresponds to the ratio of the true positive rate divided by the false positive rate (sensitivity/(1−specificity)).

Positive predictive value (PPV)

The proportion of people with a positive test result who have the condition (where having the condition is indicated by the gold standard test being positive).

Power See statistical power.

Prospective study A study in which people are entered into the research and then followed up over a period of time with future events recorded as they happen. This contrasts with studies that are retrospective.

P value If a study is done to compare two treatments then the P value is the probability of obtaining the results of that study, or something more extreme, if there really was no difference between treatments. (The assumption that there really is no difference between treatments is called the ‘null hypothesis’.) Suppose the P value was 0.03. What this means is that, if there really was no difference between treatments, there would only be a 3% chance of getting the kind of results obtained. Since this chance seems quite low we should question the validity of the assumption that there really is no difference between treatments. We would conclude that there probably is a difference between treatments. By convention, where the value of P is below 0.05 (i.e. less than 5%) the result is seen as statistically significant. Where the value of P is 0.001 or less, the result is seen as highly significant. P values just tell us whether an effect can be regarded as statistically significant or not. In no way do they relate to how big the effect might be, for which we need the confidence interval.

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Qualitative research Qualitative research is used to explore and understand people’s beliefs, experiences, attitudes, behaviour and interactions. It generates non-numerical data, e.g. a patient’s description of their pain rather than a measure of pain. In health care, qualitative techniques have been commonly used in research documenting the experience of chronic illness and in studies about the functioning of organisations. Qualitative research techniques such as focus groups and in-depth interviews have been used in one-off projects commissioned by guideline development groups to find out more about the views and experiences of patients and carers.

Quality-adjusted life years (QALYs)

A measure of health outcome that looks at both length of life and quality of life. QALYs are calculated by estimating the years of life remaining for a person following a particular care pathway and weighting each year with a quality of life score (on a zero to one scale). One QALY is equal to 1 year of life in perfect health, or 2 years at 50% health, and so on.

Quantitative research Research that generates numerical data or data that can be converted into numbers, for example clinical trials or the National Census, which counts people and households.

Random allocation or randomisation

A method that uses the play of chance to assign participants to comparison groups in a research study; for example, by using a random numbers table or a computer-generated random sequence. Random allocation implies that each individual (or each unit in the case of cluster randomisation) being entered into a study has the same chance of receiving each of the possible interventions.

Randomised controlled trial

A study to test a specific drug or other treatment in which people are randomly assigned to two (or more) groups: one (the experimental group) receiving the treatment that is being tested, and the other (the comparison or control group) receiving an alternative treatment, a placebo (dummy treatment) or no treatment. The two groups are followed up to compare differences in outcomes to see how effective the experimental treatment was. (Through randomisation, the groups should be similar in all aspects apart from the treatment they receive during the study.)

Relative risk (RR) A summary measure which represents the ratio of the risk of a given event or outcome (e.g. an adverse reaction to the drug being tested) in one group of subjects compared with another group. When the ‘risk’ of the event is the same in the two groups the relative risk is 1. In a study comparing two treatments, a relative risk of 2 would indicate that patients receiving one of the treatments had twice the risk of an undesirable outcome than those receiving the other treatment. Relative risk is sometimes used as a synonym for risk ratio.

Reliability Reliability refers to a method of measurement that consistently gives the same results. For example, someone who has a high score on one occasion tends to have a high score if measured on another occasion very soon afterwards. With physical assessments it is possible for different clinicians to make independent assessments in quick succession and if their assessments tend to agree then the method of assessment is said to be reliable.

Retrospective study A retrospective study deals with the present and past and does not involve studying future events. This contrasts with studies that are prospective.

Risk ratio Ratio of the risk of an undesirable event or outcome occurring in a group of patients receiving experimental treatment compared with a comparison (control) group. The term relative risk is sometimes used as a synonym of risk ratio.

Sample A part of the study’s target population from which the subjects of the study will be recruited. If subjects are drawn in an unbiased way from a particular population, the results can be generalised from the sample to the population as a whole.

Screening Screening is a public health service in which members of a defined population, who do not necessarily perceive they are at risk of, or are already affected by a disease or its complications, are asked a question or offered a test, to identify those individuals who are more likely to be helped than harmed by further tests or treatment to reduce the risk of a disease or its complications.

Selection criteria Explicit standards used by guideline development groups to decide which studies should be included and excluded from consideration as potential sources of evidence.

Sensitivity In diagnostic testing, sensitivity refers to the proportion of cases with the target condition correctly identified by the diagnostic test out of all the cases that have the target condition.

Specificity In diagnostic testing, specificity refers to the proportion of cases without the target condition correctly identified by the diagnostic test out of all the cases that do not have the target condition.

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Statistical power The ability of a study to demonstrate an association or causal relationship between two variables, given that an association exists. For example, 80% power in a clinical trial means that the study has a 80% chance of ending up with a P value of less than 5% in a statistical test (i.e. a statistically significant treatment effect) if there really was an important difference (e.g. 10% versus 5% mortality) between treatments. If the statistical power of a study is low, the study results will be questionable (the study might have been too small to detect any differences). By convention, 80% is an acceptable level of power. See also P value.

Study type The kind of design used for a study. Randomised controlled trials, case–control studies and cohort studies are all examples of study types.

Systematic review A review in which evidence from scientific studies has been identified, appraised and synthesised in a methodical way according to predetermined criteria. May or may not include a meta-analysis.

Technology appraisal A technology appraisal, as undertaken by NICE, is the process of determining the clinical and cost-effectiveness of a health technology. NICE technology appraisals are designed to provide patients, health professionals and managers with an authoritative source of advice on new and exisiting health technologies.

Test A procedure conducted to look for a pre-defined target of interest – either in terms of its presence/absence, or the amount/level contained in the body or a body fluid.

Validity Assessment of how well a tool or instrument measures what it is intended to measure.

Variable A measurement that can vary within a study, e.g. the age of participants. Variability is present when differences can be seen between different people or within the same person over time, with respect to any characteristic or feature that can be assessed or measured.

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1 Introduction

1.0 Introduction

The original antenatal care guideline was published by NICE in 2003. Since then a number of important pieces of evidence have become available, particularly concerning gestational diabetes, haemoglobinopathy and ultrasound, so that the update was initiated. This update has also provided an opportunity to look at a number of aspects of antenatal care:

• the development of a method to assess women for whom additional care is necessary (the ‘antenatal assessment tool’)

• information giving to women• lifestyle:

– vitamin D supplementation– alcohol consumption

• screening for the baby:– use of ultrasound for gestational age assessment and screening for fetal abnormalities– methods for determining normal fetal growth– placenta praevia

• screening for the mother:– haemoglobinopathy screening– gestational diabetes– pre-eclampsia and preterm labour– chlamydia.

1.1 Aim of the guideline

The ethos of this guideline is that pregnancy is a normal physiological process and that, as such, any interventions offered should have known benefits and be acceptable to pregnant women. The guideline has been developed with the following aims: to offer information on best practice for baseline clinical care of all pregnancies and comprehensive information on the antenatal care of the healthy woman with an uncomplicated singleton pregnancy. It provides evidence-based information for clinicians and pregnant women to make decisions about appropriate treatment in specific circumstances. The guideline will complement the Children’s National Service Frameworks (England and Wales) (2004) which provides standards for service configuration, with emphasis on how care is delivered and by whom, including issues of ensuring equity of access to care for disadvantaged women and women’s views about service provision (For more information, see www.dh.gov.uk/en/Healthcare/NationalServiceFrameworks/ChildrenServices/index.htm for England and www.wales.nhs.uk/ sites3/page.cfm?orgid=334&pid=934 for Wales). The guideline has also drawn on the evidence-based recommendations of the UK National Screening Committee (NSC).

The Changing Childbirth report1 (1993) and Maternity Matters635 (2007) explicitly confirmed that women should be the focus of maternity care with an emphasis on providing choice, easy access and continuity of care. Care during pregnancy should enable a woman to make informed decisions, based on her needs, having discussed matters fully with the professionals involved.

Reviews of women’s views on antenatal care, including a comprehensive national survey conducted by the National Perinatal Epidemiology Unit,994 suggest that key aspects of care valued by women are respect, competence, communication, support and convenience.2 Access to information and provision of care by the same small group of people are also key aspects of care that lend themselves to a pregnant woman feeling valued as an individual and more in control.3

Current models of antenatal care originated in the early decades of the 20th century. The pattern of visits recommended at that time (monthly until 30 weeks, then fortnightly to 36 weeks and then

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weekly until delivery) is still recognisable today. It has been said that antenatal care has escaped critical assessment.4 Both the individual components and composite package of antenatal care should conform to the criteria for a successful screening programme, namely that:

• the condition being screened for is an important health problem• the screening test (further diagnostic test and treatment) is safe and acceptable• the natural history of the condition is understood• early detection and treatment has benefit over later detection and treatment• the screening test is valid and reliable• treatments or interventions should be effective• there are adequate facilities for confirming the test results and resources for treatment• the objectives of screening justify the costs.

A complete list of the NSC criteria for screening can be found in the NSC online library (www.nsc.nhs.uk/library/lib_ind.htm) under the title, The UK National Screening Committee’s criteria for appraising the viability, effectiveness and appropriateness of a screening programme.

1.2 Areas outside the remit of the guideline

The guideline will not produce standards for service configuration, which have been addressed by the Children’s National Service Frameworks (England and Wales), nor will it address quality standard issues (such as laboratory standards), which are addressed by the National Screening Committee.5

Although the guideline addresses screening for many of the complications of pregnancy, it does not include information on the investigation and appropriate ongoing management of these complications if they arise in pregnancy (for example, the management of pre-eclampsia, fetal anomalies and multiple pregnancies).

Any aspect of intrapartum and postpartum care has not been included in this guideline. This includes preparation for birth and parenthood, risk factor assessment for intrapartum care, breastfeeding and postnatal depression. These topics will be addressed in future National Institute for Clinical Excellence (NICE) guidelines on intrapartum and postpartum care. In addition, preconception care is not covered in this guideline.

The guideline offers recommendations on baseline clinical care for all pregnant women but it does not offer information on the additional care that some women will require. Pregnant women with the following conditions usually require care additional to that detailed in this guideline:

• cardiac disease, including hypertension• renal disease• hepatic disease• endocrine disorders or diabetes• psychiatric disorders (on medication)• haematological disorders, including sickle cell or thalassaemia, thromboembolic disease,

autoimmune diseases such as antiphospholipid syndrome• epilepsy requiring anticonvulsant drugs• malignant disease• severe asthma• drug use such as heroin, cocaine (including crack cocaine) and ecstasy• HIV or hepatitis B virus (HBV) infected• cystic fibrosis• autoimmune disorders• obesity (body mass index, BMI, 35 kg/m² or more at first contact) or underweight (BMI less

than 18 kg/m² at first contact)• women who may be at higher risk of developing complications e.g. women 40 years and

older and women who smoke• women who are particularly vulnerable (e.g. women 18 years or younger) or who lack social

support• family history of genetic disorder• multiple pregnancy

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• women who have experienced any of the following in previous pregnancies:– recurrent miscarriage (three or more consecutive pregnancy losses) or a mid-trimester loss– severe pre-eclampsia, HELLP syndrome or eclampsia– rhesus isoimmunisation or other significant blood group antibodies– uterine surgery including caesarean section, myomectomy or cone biopsy– antenatal or postpartum haemorrhage on two occasions– retained placenta on two occasions– puerperal psychosis– grand multiparity (more than six pregnancies)– a stillbirth or neonatal death– a small-for-gestational-age (SGA) infant (less than fifth centile)– a large-for-gestational-age (LGA) infant (greater than 95th centile)– a baby weighing less than 2500 g or more than 4500 g– a baby with a congenital anomaly (structural or chromosomal).

1.3 For whom is the guideline intended?

This guideline is of relevance to those who work in or use the National Health Service (NHS) in England and Wales:

• professional groups who share in caring for pregnant women, such as obstetricians, midwives, radiographers, physiotherapists, anaesthetists, general practitioners, paediatricians, pharmacists and others

• those with responsibilities for commissioning and planning maternity services, such as primary care trusts in England, Health Commission Wales, public health and trust managers

• pregnant women.

A version of this guideline for pregnant women, their partners and the public is available from the NICE website (www.nice.org.uk/CG062publicinfo) or from NICE publications on 0845 003 7783 (quote reference number N1483).

1.4 Who has developed the guideline?

The Guideline was developed by a multi-professional and lay working group, the Guideline Development Group (GDG), convened by the National Collaborating Centre for Women’s and Children’s Health (NCC-WCH). Membership included:

• two service user representatives• two general practitioners• two midwives• two obstetricians• a radiographer• a neonatologist• a representative from the Confidential Enquiry into Maternal Deaths (CEMD).

Staff from NCC-WCH provided methodological support for the guideline development process, undertook the systematic searches, retrieval and appraisal of the evidence and wrote successive drafts of the document.

In accordance with the NICE guideline development process,6 all GDG members have made and updated any declarations of interest.

1.5 Who has developed the guideline update?

The guideline update was developed by a multi-professional and lay working group, the Guideline Development Group (GDG), convened by the National Collaborating Centre for Women’s and Children’s Health (NCC-WCH). Membership included:

• two service user representatives• two midwives

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• two obstetricians• a general practitioner• an ultrasonographer• an MRC-funded public health research fellow.

Staff from NCC-WCH provided methodological support for the guideline development process, undertook the systematic searches, retrieval and appraisal of the evidence and wrote successive drafts of the document.

In accordance with the NICE guideline development process,6 all GDG members have made and updated any declarations of interest (Appendix A).

1.6 Guideline methodology

The development of the guideline was commissioned by the National Institute for Health and Clinical Excellence (NICE) and developed in accordance with the guideline development process outlined in The Guideline Development Process – Information for National Collaborating Centres and Guideline Development Groups, available from the NICE website (www.nice.org.uk).6

Update methodology

The guideline update was developed in accordance with the NICE guideline development process outlined in the 2006 and 2007 editions of the guidelines manual.632,633 Table 1.1 summarises the key stages of the guideline development process and which version of the process was followed at each stage.

Table 1.1  Stages in the NICE guideline development process and the versions followed at each stage

Stage 2006 version 2007 versionScoping the guideline (determining what the guideline would and would not cover)

Preparing the work plan (agreeing timelines, milestones, Guideline Development Group constitution, etc.)

Forming and running the Guideline Development Group Developing clinical questions Identifying the evidence Reviewing and grading the evidence Incorporating health economics Making group decisions and reaching consensus Linking guidance to other NICE guidance Creating guideline recommendations Developing clinical audit criteria Writing the guideline Validation (stakeholder consultation on the draft guideline) Declaration of interestsa a The process for declaring interests was extended in November 2006 to cover NCC-WCH staff and to include personal

family interests.

Literature search strategy

The aim of the literature review was to identify and synthesise relevant evidence within the published literature, in order to answer the specific clinical questions. Searches were performed using generic and specially developed filters, relevant MeSH (medical subject headings) terms and free-text terms. Details of all literature searches are available upon application to the NCC-WCH.

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Guidelines by other development groups were searched for on the National Guidelines Clearinghouse database, the TRIP database and OMNI service on the Internet. The reference lists in these guidelines were checked against the searches to identify any missing evidence.

Searches were carried out for each topic of interest. The Cochrane Database of Systematic Reviews, up to Issue 3, 2003, was searched to identify systematic reviews of randomised controlled trials, with or without meta-analyses and randomised controlled trials. The electronic database, MEDLINE (Ovid version for the period January 1966 to April 2003), EMBASE (Ovid version from January 1980 to April 2003), MIDIRS (Midwives Information and Resource Service), CINAHL (Cumulative Index to Nursing and Allied Health Literature), the British Nursing Index (BNI) and PsychInfo were also searched.

The Database of Abstracts and Reviews of Effectiveness (DARE) was searched. Reference lists of non-systematic review articles and studies obtained from the initial search were reviewed and journals in the RCOG library were hand-searched to identify articles not yet indexed. There was no systematic attempt to search the ‘grey literature’ (conferences, abstracts, theses and unpublished trials).

A preliminary scrutiny of titles and abstracts was undertaken and full papers were obtained if they appeared to address the GDG’s question relevant to the topic. Following a critical review of the full version of the study, articles not relevant to the subject in question were excluded. Studies that did not report on relevant outcomes were also excluded. Submitted evidence from stakeholders was included where the evidence was relevant to the GDG clinical question and when it was either better or equivalent in quality to the research identified in the literature searches.

The economic evaluation included a search of:

• NHS Economic Evaluations Database (NHS EED)• Health Economic Evaluation Database (HEED)• Cochrane Database of Systematic Reviews, Issue 3, 2003• MEDLINE January 1966 to April 2003• EMBASE 1980 to April 2003.

Relevant experts in the field were contacted for further information.

The search strategies were designed to find any economic study related to specific antenatal screening programmes. Abstracts and database reviews of papers found were reviewed by the health economist and were discarded if they appeared not to contain any economic data or if the focus of the paper did not relate to the precise topic or question being considered (i.e. to screening strategy alternatives that were not relevant to this guideline). Relevant references in the bibliographies of reviewed papers were also identified and reviewed. These were assessed by the health economists against standard criteria.

Literature search strategy for the 2008 update

Relevant published evidence to inform the guideline development process and answer the clinical questions was identified by systematic search strategies. Additionally, stakeholder organisations were invited to submit evidence for consideration by the GDG provided it was relevant to the clinical questions and of equivalent or better quality than evidence identified by the search strategies.

Systematic searches to answer the clinical questions formulated and agreed by the GDG were executed using the following databases via the ‘Ovid’ platform: Medline (1966 onwards), Embase (1980 onwards), Cumulative Index to Nursing and Allied Health Literature (1982 onwards) and PsycINFO (1967 onwards). The most recent search conducted for the three Cochrane databases (Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and the Database of Abstracts of Reviews of Effects) was during Quarter 1, 2007. Searches to identify economic studies were undertaken using the above databases, and the NHS Economic Evaluations Database (NHS EED).

Search strategies combined relevant controlled vocabulary and natural language in an effort to balance sensitivity and specificity. Unless advised by the GDG, searches were not date specific. Language restrictions were not applied to searches. Both generic and specially developed methodological search filters were used appropriately.

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There was no systematic attempt to search grey literature (conferences, abstracts, theses and unpublished trials). Hand searching of journals not indexed on the databases was not undertaken.

Towards the end of the guideline development process searches were re-executed, thereby including evidence published and included in the databases up to 8 June 2007. Any evidence published after this date was not included. This date should be considered the starting point for searching for new evidence for future updates to this guideline.

Further details of the search strategies, including the methodological filters employed, are available on an accompanying disc.

Clinical effectiveness

For all the subject areas, evidence from the study designs least subject to sources of bias was included. Where possible, the highest levels of evidence were used, but all papers were reviewed using established guides (see below). Published systematic reviews or meta-analyses were used if available. For subject areas where neither was available, other appropriate experimental or observational studies were sought.

Identified articles were assessed methodologically and the best available evidence was used to form and support the recommendations. The highest level of evidence was selected for each clinical question. Using the evidence-level structure shown in Table 1.2, the retrieved evidence was graded accordingly.

Table 1.2 Structure of evidence levels

Level Definition1a Systematic review and meta-analysis of randomised controlled trials1b At least one randomised controlled trial2a At least one well-designed controlled study without randomisation2b At least one other type of well-designed quasi-experimental study3 Well-designed non-experimental descriptive studies, such as comparative studies, correlation

studies or case studies4 Expert committee reports or opinions and/or clinical experience of respected authorities

Hierarchy of evidence

The clinical question dictates the highest level of evidence that should be sought. For issues of therapy or treatment, the highest level of evidence is meta-analyses of randomised controlled trials or randomised controlled trials themselves. This would equate to a grade A recommendation.

For issues of prognosis, a cohort study is the best level of evidence available. The best possible level of evidence would equate to a grade B recommendation. It should not be interpreted as an inferior grade of recommendation, as it represents the highest level of evidence attainable for that type of clinical question.

For diagnostic tests, test evaluation studies examining the performance of the test were used if the efficacy of the test was required. Where an evaluation of the effectiveness of the test on management and outcome was required, evidence from randomised controlled trials or cohort studies was sought.

All retrieved articles have been appraised methodologically using established guides. Where appropriate, if a systematic review, meta-analysis or randomised controlled trial existed in relation to a topic, studies of a weaker design were not sought.

The evidence was synthesised using qualitative methods. These involved summarising the content of identified papers in the form of evidence tables and agreeing brief statements that accurately reflect the relevant evidence. Quantitative techniques (meta-analyses) were performed if appropriate and necessary.

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For the purposes of this guideline, data are presented as relative risk (RR) where relevant (i.e. in RCTs and cohort studies) or as odds ratios (OR) where relevant (i.e. in systematic reviews of RCTs). Where these data are statistically significant they are also presented as numbers needed to treat (NNT), if relevant.

Appraisal and synthesis of clinical effectiveness evidence for the 2008 update

Evidence relating to clinical effectiveness was reviewed and classified using the established hierarchical system presented in Table 1.3.632,633 This system reflects the susceptibility to bias that is inherent in particular study designs.

The type of clinical question dictates the highest level of evidence that may be sought. In assessing the quality of the evidence, each study was assigned a quality rating coded as ‘++’, ‘+’ or ‘−‘. For issues of therapy or treatment, the highest possible evidence level (EL) is a well-conducted systematic review or meta-analysis of randomised controlled trials (RCTs; EL = 1++) or an individual RCT (EL = 1+). Studies of poor quality were rated as ‘−‘. Usually, studies rated as ‘−’ should not be used as a basis for making a recommendation, but they can be used to inform recommendations. For issues of prognosis, the highest possible level of evidence is a cohort study (EL = 2). A level of evidence was assigned to each study appraised during the development of the guideline.

For each clinical question, the highest available level of evidence was selected. Where appropriate, for example, if a systematic review, meta-analysis or RCT existed in relation to a question, studies of a weaker design were not considered. Where systematic reviews, meta-analyses and RCTs did not exist, other appropriate experimental or observational studies were sought. For diagnostic tests, test evaluation studies examining the performance of the test were used if the effectiveness (accuracy) of the test was required, but where an evaluation of the effectiveness of the test in the clinical management of patients and the outcome of disease was required, evidence from RCTs or cohort studies was optimal. For studies evaluating the accuracy of a diagnostic test, sensitivity, specificity, positive predictive values (PPVs) and negative predictive values (NPVs) were calculated or quoted where possible (see Table 1.4).

Table 1.3 Levels of evidence for intervention studies

Level Source of evidence

1++ High-quality meta-analyses, systematic reviews of randomised controlled trials (RCTs), or RCTs with a very low risk of bias

1+ Well-conducted meta-analyses, systematic reviews of RCTs, or RCTs with a low risk of bias

1− Meta-analyses, systematic reviews of RCTs, or RCTs with a high risk of bias

2++ High-quality systematic reviews of case–control or cohort studies; high-quality case–control or cohort studies with a very low risk of confounding, bias or chance and a high probability that the relationship is causal

2+ Well-conducted case–control or cohort studies with a low risk of confounding, bias or chance and a moderate probability that the relationship is causal

2− Case–control or cohort studies with a high risk of confounding, bias or chance and a significant risk that the relationship is not causal

3 Non-analytical studies (for example, case reports, case series)

4 Expert opinion, formal consensus

Table 1.4 ’2 × 2’ table for calculation of diagnostic accuracy parameters

Reference standard positive Reference standard negative Total

Test positive a (true positive) b (false positive) a+b

Test negative c (false negative) d (true negative) c+d

Total a+c b+d a+b+c+d = N (total number of tests in study)

Sensitivity = a/(a+c), specificity = d/(b+d), PPV = a/(a+b), NPV = d/(c+d)

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Antenatal care

The system described above covers studies of treatment effectiveness. However, it is less appropriate for studies reporting accuracy of diagnostic tests. In the absence of a validated ranking system for this type of test, NICE has developed a hierarchy of evidence that takes into account the various factors likely to affect the validity of these studies (see Table 1.5).633

Table 1.5 Levels of evidence for studies of the accuracy of diagnostic tests

Level Type of evidence

Ia Systematic review (with homogeneity)a of level-1 studiesb

Ib Level-1 studiesb

II Level-2 studiesc; systematic reviews of level-2 studies

III Level-3 studiesd; systematic reviews of level-3 studies

IV Consensus, expert committee reports or opinions and/or clinical experience without explicit critical appraisal; or based on physiology, bench research or ‘first principles’

a Homogeneity means there are no or minor variations in the directions and degrees of results between individual studies that are included in the systematic review.

b Level-1 studies are studies that use a blind comparison of the test with a validated reference standard (gold standard) in a sample of patients that reflects the population to whom the test would apply.

c Level-2 studies are studies that have only one of the following:• narrow population (the sample does not reflect the population to whom the test would apply)• use a poor reference standard (defined as that where the ‘test’ is included in the ‘reference’, or where the ‘testing’

affects the ‘reference’)• the comparison between the test and reference standard is not blind• case–control studies.

d Level-3 studies are studies that have at least two or three of the features listed above.

Health economics

In antenatal care, there is a relatively large body of economic literature that has considered the economic costs and consequences of different screening programmes and considered the organisation of antenatal care. The purpose of including economic evidence in a clinical guideline is to allow recommendations to be made not just on the clinical effectiveness of different forms of care, but on the cost-effectiveness as well. The aim is to produce guidance that uses scarce health service resources efficiently; that is, providing the best possible care within resource constraints.

The economic evidence is focused around the different methods of screening, although some work has been undertaken to examine the cost-effectiveness of different patterns of antenatal care (the number of antenatal appointments) and to explore women’s preferences for different aspects of their antenatal care. The economic evidence presented in this guideline is not a systematic review of all the economic evidence around antenatal care. It was decided that the health economic input into the guideline should focus on specific topics where the GDG thought that economic evidence would help them to inform their decisions. This approach was made on pragmatic grounds (not all the economic evidence could be reviewed with the resources available) and on the basis that economic evidence should not be based only on the economic literature, but should be consistent with the clinical effectiveness evidence presented in the guideline. Some of the economic evaluation studies did not address the specific alternatives (say, for screening) that were addressed in the guideline. Therefore, for each of the specific topic areas where the economic evidence was reviewed, a simple economic model was developed in order to present the GDG with a coherent picture of the costs and consequences of the decisions based on the clinical and economic evidence. The role of the health economist in this guideline was to review the literature in these specific areas and obtain cost data considered to be the closest to current UK opportunity cost (the value of the resources used, rather than the price or charge).

The approach adopted for this guideline was for the health economic analysis to focus on specific areas. Topics for economic analysis were selected on the following basis by the GDG.

• Does the proposed topic have major resource implications?• Is there a change of policy involved?

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• Are there sufficient data of adequate quality to allow useful review or modelling?• Is there a lack of consensus among clinicians?• Is there a particular area with a large amount of uncertainty?

Where the above answers were ‘yes’, this indicated that further economic analysis including modelling is more likely to be useful.

The GDG identified six areas where the potential impact of alternative strategies could be substantial and where the health economics evidence should focus. These were: screening for asymptomatic bacteriuria, screening for group B streptococcus, screening for syphilis, screening for sickle cell and thalassaemia, ultrasound screening for structural abnormalities and Down’s syndrome screening.

For all these topics, a review of the economic evidence was undertaken, followed by simple economic modelling of the cost-effectiveness in England and Wales of different strategies.

The review of the economic evaluation studies included cost-effectiveness studies (only those where an ICER had been determined or could be determined from the data presented). The topic had to focus on the appropriate alternatives (the appropriate clinical question), preferably able to be generalised to the England and Wales setting, and therefore be useful in constructing a simple decision model. The review of the evidence included cost-effectiveness studies, cost-consequence studies (cost of present and future costs only) and high-quality systematic reviews of the evidence. A narrative review of all the evidence is not presented in the main guideline. Appendices B to F shows the way the models have been constructed, the economic and clinical parameters incorporated into each model, the sources of data that have been used (cost data and clinical data), the results of the baseline model and the sensitivity analysis.

Evidence on the cost consequences associated with alternative screening strategies was obtained from various published sources that addressed these issues. The purpose was to obtain good-quality cost data judged by the health economist to be as close as possible to the true opportunity cost of