copyright © houghton mifflin harcourt publishing company. all rights reserved. 1) first stage of...

Copyright © Houghton Mifflin Harcourt Publishing Company. All rights reserved.

1) First Stage of Prenatal Development: Germinal Stage

– Conception to implantation– Approximately 2 weeks

• Timeline– Cell division or mitosis begins 24 hours post fertilization– 2-3 days to reach uterus

• 12-16 cells = blastocycst– Implantation fully complete after 2 weeks

• Thousands of cells• Cell differentiation begins


2) The 2nd Stage: The Embryonic Stage– Implantation to 8 weeks– Major organs and body

systems develop• Amnio

– Membrane which grows over embryo and fills with amniotic fluid

– Protects embryo• Chorion

– Membrane that grows around embryo and becomes the placenta

– After 1 mo. of development

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• Placenta– The structure through which

nutrients and waste products are exchanged

• Umbilical cord– The lifeline of the embryo,

connecting it to the placenta– Consists of two arteries and

one vein

• During embryonic period, all major systems form

• Thus, this is a time of great vulnerability


Developmental Principles

• Cephalocaudal development– The principle that growth occurs from the head

downward

• Proximodistal development– The principle that body parts closer to the central

axis of the body develop first


Stage 3: The Fetal Stage• 8 weeks to Birth• Marked by growth

and elaboration of structures developed earlier

• Quickening– Fetal movements

during pregnancy felt by the mother

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The Fetal Stage• Rapid rate of growth• 3rd month of gestation

– Sexual differentiation occurs– Male genital development triggered by testosterone

release

• 5th month– Cells of the brain have migrated and formed

connections with other brain cells– Now can communicate with each other and control

some body functions– Simple reflex actions appear


The Fetal Stage

• Age of viability– Age at which postnatal survival is likely– 7 months gestation (22 weeks)

• Newborn– average is 7-7.5 pounds – and 20 inches long


Environmental Influences

• Developing fetuses are protected by– Amniotic fluid– Placental barrier

• Teratogens– Agents that cross the placental barrier and

adversely affect development– Diseases, Drugs, Environmental Hazards


Factors Affecting Teratogenic Influence

• Time of exposure– Teratogens exert their effects on currently

developing systems

• Amount of exposure– The longer or greater the exposure, the worse the

effect

• Fetal characteristics– Individual differences influence the strength of

effects


Maternal Age

• Advanced maternal age is increasingly common

• Risks of increased age– Down syndrome– High blood pressure– Gestational diabetes– Cardiovascular disease– Miscarriage


Maternal Stress

• Stress causes changes in mom’s blood chemistry.

• Pregnant women who are highly stressed are at increased risk of:– Miscarriage– Complicated deliveries– Birthing prematurely


Parity• Parity

– The number and spacing of children a woman bears

• Body takes 4 years to return to prepregnancy condition– Infants born before recovery may be

disadvantaged• Later-born children have

– A richer blood supply– Fewer birth defects and complications– Quicker deliveries


Protective Factors1) Nutrition• Pregnant women

– Need about 300 extra calories/day– Need increased levels of iron, protein, folic acid, calcium

and phosphorus• Ideal weight gain is about 30 pounds• Birth defects

– Women who do not have adequate folate are at risk of neural tube defects

• Anencephaly• Spina bifida

– Half of neural tube defects in the U.S. are caused by inadequate folate intake


2) Exercise– Provides pregnant women with more energy– Builds bones and muscles– Generally improves health– May improve women’s ability to cope with childbirth

pain

3) Prenatal Care– Regular prenatal care is associated with lower rates of

birth complications– Many women do not receive adequate prenatal care– Pre-natal testing


4) Social Support• Having social support helps a

woman– Manage stress– Deal with physical demands

and complications during pregnancy

– Benefits of having a partner– Correlation between mother

and father’s stress

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The Birth Process• gestation is from 37-41 weeks • Lightening (2-3 weeks before delivery)

– sensation that occurs when fetus drops into the pelvic cavity in preparation for birth

• what triggers labor?– fetal release of steroids from adrenal glands– maternal release of prostoglandins or oxytocin

Stages of the Birth Process:1. Dilation of Cervix2. Expulsion of Fetus3. Expulsion of Placenta


Normal Uncomplicated Birth

17


What women are at risk for complications?

• Adolescent girls• Older women, especially primiparous

mothers over 35• Women with certain diseases or conditions

(e.g., diabetes, obesity, malnutrition)• Women carrying multiple babies


Birth Complications: Cesarean Sections

• Procedure by which the fetus is delivered through an incision in the mother’s abdomen

• Used – When delays in labor endanger the baby– When the baby is in a breech or transverse position– Unfavorable shape of pelvis– Placenta previa or placenta abrupto– Eclampsa– Prolonged labor– diabetes


Birth Complications

20


Cesarean Sections

• There has been a sharp rise in c-sections in the past three decades

• Many factors account for the rise• While c-sections can be effective, they carry

increased risks


Induced Labor

• Sometimes allowing a pregnancy to continue is dangerous for mother or child

• Labor can be induced– Pitocin used to stimulate contractions

• Induction rates have increased


APGAR scale

• A quick method of diagnosing potential problems in newborns

• 5 vital signs are assessed– Respiration– Reflex responsiveness– Muscle tone– Respiration– Color– Heart rate


Newborns at Risk• Preterm

– A.k.a. premature– Babies born prior to 37 weeks gestation

• Small for Gestational Age– Babies born after 37 weeks gestation but weighing less

than 5 pounds

• Both are high risk• Low Birth Weight, Very Low Birth Weight,

Extremely low Birth Weight• Rates vary by racial/ethnic group


Consequences

• Many children develop normally and are healthy– Plasticity of nervous system– Resilience

• Potential issues include– Subnormal growth– Mental retardation– Blindness– Deafness– Cerebral palsy– Health problems


The Mother’s Perspective

• Baby blues– Common experience of intense emotionality

following childbirth– Contributions

• Biological changes• Fatigue• Loss of attention• Increased demands at home• Sense of anticlimax• Feelings of inadequacy


The Mother’s Perspective• Postpartum Depression

– An episode of clinical depression triggered by childbirth

– Causes?• Biological changes• Stressful life events• Delivery complications• Sleep deprivation

– Often requires medical treatment

•Postpartum Psychosis

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