PRETERM LABOR

Osama M Warda MDAssistant professor of Obstetrics & Gynecology-Mansoura University- EGYPT

DEFINITION………………(WHO)

Preterm labor is the presence of

contractions of sufficient

strength and frequency to effect

progressive effacement and

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progressive effacement and

dilation of the cervix between 20

and 37 weeks' gestation

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INCIDENCE

� Total incidence = 6-10%of all pregnancies

� Spontaneous = 40-50% (of total PL)

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� PROM= 25-40%

� Obstetrically indicated = 20-25%

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COMPLICATIONS OF PRETERM BIRTH

Most of mortality and morbidity are experienced by

babies born before34 weeks gestation

Major neonatal risks include:1- Death

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1- Death 2- Respiratory distress syndrome 3- Hypothermia 4- Hypoglycaemia5- Necrotising enterocolitis6- Jaundice 7- Infection 8- Retinopathy of prematurity

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RISK FACTORS FOR PRETERM LABOR

While the exact cause of preterm labor is often

unknown, there is strong evidence that

intrauterine infection may play a role in

very early preterm labor.

Bacterial vaginosis increased the risk of

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Bacterial vaginosis increased the risk of

preterm delivery >2-fold .

Risks were higher for those screened (at

<16 weeks) than those (at <20 weeks of

gestation ). 5

RISK FACTORS FOR PRETERM LABOR,

Other risk factors include:

1. Multiple pregnancy: risk >50%

2. Previous preterm delivery: risk 20- 40%

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3. Cigarette smoking: risk 20-30%

4. Cervical incompetence

5. Uterine abnormalities

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RISK FACTORS FOR PRETERM LABOR, CONT.,

Other risk factors include:( cont.,)

6. Young age of mother - less than 16 years

7. Lower socioeconomic status.

8. Reduced body mass index (BMI<19kg/m2)

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8. Reduced body mass index (BMI<19kg/m2)

9. Antiphosphlipid syndrome.

10. Obstetric complications, including PIH,

APHge, infection, polyhydramnios, foetal

abnormalities.

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PREDICTION OF PRETERM LABOR

1. Assessment of risk factors

2. Vaginal examination to assess the

cervical status

3. Ultrasound visualization of

cervical length and dilatation

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cervical length and dilatation

4. Detection of fetal fibronectin in

cervico-vaginal secretions

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PREDICTION OF PRETERM LABOR; (CONT.)

� VAGINAL

EXAMINATION

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Digital examination is the traditional

method used to detect cervical

maturation, but quantifying

these changes is often difficult.9

PREDICTION OF PRETERM LABOR; (CONT.)

ENDOVAGINAL ULTRASOUND EVALUATION OF THE CERVIX

Vaginal ultrasonography allows a more objective

approach to examination of the cervix. “ 12-16wk”

normal cx canal length ≥ 35mm

Cervical Length RR of PTD

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<35mm 2.35

<30mm 3.79

<26mm 6.19

<22mm 9.49

<13mm 13.9910

PREDICTION OF PRETERM LABOR; (CONT.)� FETAL FIBRONECTIN TEST

(detected in cervico-vaginal secretions)

-ve FFN� Negative predictive value of 99% (good –ve)

+ve FFN

OutcomeTrophoblastGlue:

Promotes cellular Promotes cellular Promotes cellular Promotes cellular adhesion at adhesion at adhesion at adhesion at uterineuterineuterineuterine----placental placental placental placental and and and and decidualdecidualdecidualdecidual----fetal fetal fetal fetal

+ve FFN� Positive predictive value of 13-30%

Why good negative test?

99.5% of symptomatic women with

negative FFN are undelivered at 7 days

99.2% of symptomatic women with

negative FFN are undelivered at 14 days

and and and and decidualdecidualdecidualdecidual----fetal fetal fetal fetal membrane membrane membrane membrane interfacesinterfacesinterfacesinterfaces

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PREVENTION OF

PRETERM

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PRETERM

LABOR12

PREVENTION OF PRETERM LABOR

Women at increased risk of

preterm delivery may be

identified by various risk

factors in the obstetric history

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factors in the obstetric history

and treated.

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PREVENTION OF PRETERM LABOR

� Supplemental progesterone� 17OHP – start 2nd trimester, continue until 36 weeks if

prior delivery before 34 wks (17OHP use in high risk women reduced PTB by 15-70%)

� QUIT SMOKING

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� Just say NO! (especially to cocaine)

� Cervical cerclage (for cvx insufficiency)

� Diagnose & treat infection� Asymptomatic bacteriuria, BV, GC, chlamydia

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DIAGNOSIS OF

PRETERM

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PRETERM

LABOR15

DIAGNOSIS OF PRETERM LABOR

3 criteria to document PTL(20-37w):

1-Regular uterine contractions occur

at 4/20 min. or 8/60 min. Plus:

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progressive change in the cervix.

2- Cervical dilatation > 1 cm

3- Cervical Effacement ±80%.

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DIAGNOSIS OF PRETERM LABOR; CONT;

Suspected preterm labor with no cervical changes :

Negative FFN { + } Cervical length > 30 mm

The likelihood of delivering in the next week is less than The likelihood of delivering in the next week is less than 11%.%.

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The likelihood of delivering in the next week is less than The likelihood of delivering in the next week is less than 11%.%.

Thus most women with a negative test can safely be

sent home without treatment.

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TREATMENT

OF

PRETERM

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PRETERM

LABOR18

TREATMENT OF PTB

�Tocolysis – inhibit myometrial contractility� Magnesium

� Terbutaline

� Indomethacine

� Nifedipine

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� Nifedipine

�Contraindications to tocolysis:� IUFD, lethal fetal anomalies, NRFHT

� Severe IUGR, chorio, hemorrhage

� Severe pre-e/eclampsia

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TOCOLYSIS

MgSO4 Terbutaline Indocin Nifedipine

Class Β-agonist Cox inhibitors CCB

Action Competes for Ca

↑ cAMP

↓ intracellular

Ca

↓ PGD

productionBlock Ca

influx

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Ca

Side Effect Pulm edema, ? ↑ ped M&M

Tachy, ↓BP, palp, ↓K, pulm

edema

N/V, gastritis, narrowing of

DA, oligo

↓BP, reflex tachy, ? ↓ of

blood flow

Efficacy Not very good!

No ↓ of PTB @

7 days, sx relief

Appears to be more effective than placebo

↓ # of women

giving birth at 7 days

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!RULELUCOCORTICOIDSG

�Why?� Reduce the risk of neonatal RDS, IVH, NEC,

and mortality by 50% (FIFTY!)

� Benefit observed 18 hours after 1st dose, max benefit @ 48 hours

� Give 24-34 wks (?24-32wks if PPROM)

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� Give 24-34 wks (?24-32wks if PPROM)

�How?� Enhance maturation of lung architecture

� Induce lung enzymes resulting in biochemical maturation

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CERVICAL CERCLAGE

�For cervical insufficiency which

complicates 0.1-2% of all pregnancies and

is responsible for 20% of late 2nd trimester

losses

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�Prophylactic cerclage – 12-14wks

�Rescue cerclage – when cvx changes

already detected22

CERVICAL CERCLAGE

• Shirodkar

•MacDonald’s

• Caspi’s

•Abdominal

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•Abdominal

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