Chapter 3

Prenatal Development and Birth (p. 67)

Modified: 2025-07-02 (4:04 PM CDST)

• A. Conception (p. 68)
  • 1. Midway through menstrual cycle (every 28 days or so), ovum is released
    • a. Egg usually disintegrates and leaves in menstrual flow.
    • b. One sperm may enter the egg.
  • 2. Infertility—not being able to get pregnant after a year of trying
    • a. Equally traced to men and women
    • b. Simple intervention methods
    • c. Assisted reproductive techniques used to increase fertility
      • i. Artificial insemination—injecting sperm of partner or donor into a woman
      • ii. In vitro fertilization (IVF)—eggs removed, manually combined with sperm, implanted into the uterus
• B. Perinatal Stages (p. 69)
  • 1. Lasts for about 266 days (9 months)
    • a. Zygote to fetus—one cell to billions
    • b. Prenatal development occurs in three stages:
      • i. Germinal period
      • ii. Period of embryo
      • iii. Period of fetus
  • 2. The Germinal Period
    • a. Lasts about 2 weeks
    • b. Zygote divides to form blastocyst—hollow ball of 150 cells the size of head of pin
  • 3. The Embryonic Period
  • a. Lasts from the third to eighth week
  • b. Organogenesis—every major organ takes shape
  • c. Blastocyst layers differentiate forming new structures
    • i. Outer layer becomes amnion—watertight membrane surrounding chorion and chorion—membrane on outside of amnion containing villi, which attach to uterine lining
    • ii. Chorion eventually becomes the lining of the placenta—tissue fed by mother’s blood vessels and connected to embryo by umbilical cord
    • iii. Nutrients and wastes are exchanged through placenta and umbilical cord
    • iv. Placental barrier—membrane through which the nutrient and small carbon dioxide molecules pass
    • d. Interior cells of blastocyst give rise to ectoderm (e.g., brain and spinal cord), mesoderm (e.g., bone, heart, kidney), and endoderm (lungs, bladder) layers
  • e. Brain development apparent after 3–4 weeks
    • i. Neural plate forms neural tube (bottom is spinal cord)
    • ii. Top of tube forms into forebrain, midbrain, hindbrain
    • iii. Spina bifida—neural tube at bottom fails to become fully enclosed and spinal cord not fully encased
    • iv. Anencephaly—tube at top fails to close, main portion of brain fails to develop
    • v. Neural tube defects occur 25–29 days after conception
    • vi. Level of folic acid in mothers critical for development of embryo
  • f. Organs (e.g., heart, eyes) take shape
  • g. Arms and legs appear
  • h. Sex differentiation
    • i. Begin existence with undifferentiated sex tissue
    • ii. About seventh to eighth prenatal week, sex genes impact formation of testes or ovaries
  • 4. The Fetal Period
    • a. Ninth prenatal week to birth
    • b. Significant brain development
      • i. Proliferation of neurons (hundreds of thousands per minute throughout pregnancy)
      • ii. Significant neural development between 10 and 20 weeks
      • iii. Young infant has around 100 billion neurons
      • iv. Increase in number of glial cells that support neural cells
      • v. Neurons migrate into position traveling along surface of glial cells and detaching at programmed destinations
      • vi. Differentiation—neurons begin to differentiate in function depending on where they have migrated
      • vii. Stem cells—early “unspecialized” cells
    • c. Organs formed in embryonic period continue to grow and function
      • i. Harmful agents no longer cause major malformations as organs already formed
    • d. Third month
      • i. Distinguishable sex organs appear
      • ii. Bones and muscle form
      • iii. By end of third month (first trimester), movement of limbs
      • e. Second trimester (months 4–6)
      • i. Refined activities (e.g., thumb sucking)
      • ii. Sensory organ functioning
      • iii. Age of viability—around 23 weeks after conception, has possibility of surviving outside uterus
    • f. Third trimester (months 6–9)
      • i. Rapid growth in length and weight
      • ii. Myelin—insulating cover on brain—begins to develop (improving ability of neurons to transmit signals)
      • iii. Infant states—organization of behavior in waking, heart rate, and sleeping patterns
      • iv. End of prenatal periods tends to be in one distinct state (e.g., active sleep)
      • v. Late in pregnancy (32 weeks), spend more time in active, waking state
      • vi. Beginning of continuity between prenatal and postnatal behavior (newborn behavior emerges long before birth)
      • vii. Contractions of uterus typically begin birth process

II. The Prenatal Environment and Fetal Programming (p. 74)

• A. Mother’s womb is the “prenatal environment” for unborn child
  • 1. Fetus is impacted by physical environment
    • a. A pregnant woman’s use of cocaine may lead to extraordinarily fussy newborn
    • b. Developing embryo-then-fetus is vulnerable
• B. Teratogens ((p. 75)
  • 1. Teratogens—any disease, drug, or environmental agent that can harm prenatal organism
    • a. Generalizations concerning teratogens
      • i. Effects are worst during critical period when organ systems are forming
      • ii. Effects determined by dosage and duration of exposure
      • iii. Susceptibility is influenced by genetic makeup of mother and fetus, and the quality of the prenatal environment
      • iv. Prenatal and postnatal environments determine critical periods—times when organism is highly sensitive to damage (also called sensitive periods)
  • 2. Drugs
    • a. Thalidomide
      • i. A type of tranquilizer widely used in Europe in the 1950s for relief of morning sickness
      • ii. Major impact (e.g., flipper limbs, deformed ears, missing thumbs) if taken between 20 and 35 days
      • iii. Banned, but now being used to treat other disorders (e.g., leprosy, AIDS), with warning to not be used by pregnant women
    • b. Tobacco
      • i. Warnings labels have decreased number of pregnant women who smoke, but about 22% of women smoke during first trimester (when some may not know they are pregnant) with rates dropping to around 14% in the second and third trimesters
      • ii. Inhibits prenatal growth, increases risk of miscarriage, retards growth of fetus, and may lead to central nervous system impairment
      • iii. More than half of infants born to women smoking 20 or more cigarettes a day end up in neonatal intensive care units
      • iv. Exposure to as few as five cigarettes a day can lead to damage
      • v. Babies of smokers more susceptible to respiratory infections and breathing difficulties
      • vi. Sudden infant death syndrome—sleeping baby suddenly stops breathing and dies; risk increases when mother smokes while pregnant
    • c. Alcohol
      • i. Alcohol consumed by mom crosses the placental barrier
      • ii. Fetal alcohol syndrome (FAS)—more severe cluster of symptoms (e.g., small size, distinct facial features) associated with alcohol consumption by pregnant women
      • iii. FAS increases risk for central nervous system damage, hyperactivity, seizures, below-average IQ scores, and attention deficit
    • d. Cocaine
      • i. Can cause spontaneous abortion, placenta detachment, or fetal strokes
      • ii. Use can contribute to fetal malnutrition
      • iii. Small proportion of infants may experience withdrawal-like symptoms after birth and experience sensory motor skill difficulties in their first year
    • e. Opioid
      • i. Smaller babies and early delivery
      • ii. Increased risk of cesarean section
      • iii. Neonatal abstinence syndrome (NAS): withdrawal from the drug
  • 3. Diseases
    • a. Rubella—German measles
      • i. In early 1940s, discovered prenatal impact that included blindness, deafness, heart defects, and brain damage
      • ii. Impact greatest during first trimester (nearly 15% of pregnant women with rubella miscarry)
      • iii. 60 to 85% of babies exposed to rubella in first 2 months have birth defects
    • b. Diabetes
      • i. Gestational diabetes is a fairly common pregnancy complication
      • ii. Controllable by diet
      • iii. Poor control increases risk for negative impacts (e.g., miscarriage, large fetal size, immature lung development)
    • c. AIDS
      • i. Can be transmitted to babies prenatally, perinatally, and postnatally
    • d. Syphilis
      • i. Sexually transmitted
      • ii. Impact includes blindness, deafness, heart defects, and brain damage
      • iii. Impact greatest later in pregnancy—cannot cross placental barrier until 18th week
      • iv. Early treatment (penicillin) can be effective but some infants still infected or die
  • 4. Environmental hazards
    • a. Radiation
      • i. Can lead to higher rates of congenital defects in children
      • ii. Expectant mothers are routinely advised to avoid X-rays
    • b. Pollutants
      • i. Lead to lower birth weight, preterm birth, and impaired intellectual functioning
• C. Maternal Factors (p. 82)
  • 1. Parents can set stage for healthy pregnancy
    • a. Better diet (good nutrition, avoiding alcohol, consuming less fish)
    • b. Quit smoking
    • c. Remaining physically active
    • d. Avoid toxins like lead in paint or parasite in cat feces that causes toxoplasmosis
    • e. Lamaze method
    • f. 1940s technique for reducing fear and pain associated with childbirth
  • 2. Age and race/ethnicity
    • a. Ages 20–40 are “safest” childbearing years.
    • b. Very young mothers have higher risk of complications, including stillbirth—fetal death late in pregnancy.
    • c. Older women have trouble getting pregnant and have an increased risk of miscarriage, stillbirth, and low-birth-weight babies.
    • d. Non-Hispanic black women have highest rate of fetal mortality.
  • 3. Emotional Condition
    • a. Damage may be due to stress hormones like adrenaline (also called epinephrine), which temporarily increase fetal motor activity.
    • b. Prolonged (chronic), severe maternal emotional stress may be damaging to fetus.
    • i. Impacts include stunted prenatal growth and irregular heart rate
    • ii. May show delays in cognitive development and more fear as young children
    • c. Mild to moderate stress may be beneficial to fetal development.
    • d. Maternal depression may negatively impact fetal development.
• D. Paternal Factors (p. 88)
  • 1. Little research on father’s contribution (beyond genetic)
    • a. Risk of miscarriage rate increases with paternal age
    • b. Elevated risk of heart defects, neural tube defects, kidney problems, and schizophrenia in children born to older dads
    • c. Risk of Down syndrome higher in infants of older men (especially if mom is older)
    • d. Father’s exposure to environmental toxin (e.g., radiation, pesticides) can damage sperm and increase risk of defects

III. The Perinatal Environment (p. 88)

• A. Perinatal Environment (social and medical environment surrounding birth) (p. 88)
  • 1. Major shift in birthing practices in Western cultures where birth has become more medical, involving technology and doctors (1930, 80% of births at home; today 1%)
    • a. Maternal–fetal specialists (perinatologist) recommended for high-risk pregnancies
    • b. Spouse, partner, mother, sister, or friends more commonly allowed in the delivery room
    • c. Some have support of a doula—individual trained to provide continuous physical and emotional support throughout the pregnancy
    • d. Support from others tends to shorten labor, reduce the use of pain medications and forceps, and result in fewer cesarean sections
  • 2. Childbirth is three-stage process
    • a. Labor
      • i. Begins with contractions of uterus and dilation of cervix
      • ii. Duration average of 9 hours for firstborn and 4–6 hours for later-born children
      • iii. Ends with dilation of cervix of 10 centimeters
    • b. Delivery of baby
      • i. Fetus passes out of uterus/cervix
      • ii. Fetus emerges from woman’s body via the vaginal opening
      • iii. Mother told to “bear down” (push)
      • iv. First deliveries about 1 hour in this stage, later deliveries short
    • c. Delivery of placenta
      • i. Lasts a few minutes
      • ii. Mothers and fathers often exhausted
• B. Possible Hazards (p. 89)
  • 1. Anoxia—oxygen shortage (also called asphyxia)
    • a. Due to umbilical cord pinched or tangled, sedatives given to mother, mucus in baby’s throat, or breech presentation (feet or buttocks first) during a vaginal delivery
    • b. Oxygen deprivation can cause death of brain cells and results in poor reflexes, seizures, breathing difficulties
    • c. Severe anoxia can cause cerebral palsy—neurological disability inhibiting muscle movement or increased risk for learning, intellectual, and speech difficulties
    • d. Mild anoxia typically does not lead to permanent problems
    • e. Fetal monitoring during labor and delivery can avoid possibility of anoxia
    • f. Fetus laying sideways in uterus may lead to cesarean section—surgical removal of baby through mother’s abdomen
  • 2. Complicated Delivery
    • a. Cesarean section (C-section) controversial form of birth
      • i. Used if baby too large, fetus out of position, when placenta prematurely separates from the uterus, or when fetal monitoring indicates a problem
      • ii. Process is safe, but mothers do take longer to recover and may be slightly less positive toward and involved with their babies during the recovery period
      • iii. Account for nearly 32% of U.S. births

VBAC: Vaginal birth after Cesarean--some mothers opt to have subsequent children following a cesarean delivery vaginally.

• 3. Medications
• a. Medications used during birth to reduce pain (analgesics and anesthetics), to relax mothers (sedatives), and to induce or intensify contractions (stimulants)
• b. Sedatives can affect baby, making it sluggish or difficult to feed or cuddle during the first few days after birth
• c. Regional analgesics (epidural or spinal block) deaden pain in area of body and have less effect on baby, but use may increase labor time and need for forceps or vacuum assistance
• d. Oxytocin (“Pitocin”) sometimes used to initiate or speed up contractions
• C. The Mother’s Experience (p. 91)
• 1. Unique experience involving many psychological factors
  • a. Attitude toward pregnancy, knowledge about birth process, sense of control over childbirth, social support from others (which is especially critical) all impact maternal birth experience
• 2. Cultural Factors
  • a. Desirability to have children varies by culture
  • b. Birth practices differ by culture
  • c. Western societies have highly “medicalized” childbirth (done in hospitals with women hooked up to monitors and separated from most friends and family)
• 3. Postpartum Depression
  • a. “Baby blues”—mild feelings of anxiety, irritability, and depression common for a few days after birth but typically fades
    • i. Possibly the result of steep drop in hormone levels, stress associated with delivery, and new responsibility of parenting
  • b. Postpartum depression—more serious post-birth feelings of anxiety, moodiness, and depression experienced by some women in months after birthing
    • i. Postnatal depression affects approximately 15–20% of new mothers; tends to be found in women with history of depression, who are experiencing other life stresses, or who have few social supports
    • ii. Influences mother–child interactions (e.g., children less attached)
    • iii. Children of postnatally depressed mothers may exhibit behavioral problems (e.g., violence) during late childhood and adolescence and show elevated levels of cortisol (associated with major depression)
    • iv. Depressed mothers tend to be unresponsive to babies and may feel hostility toward them
    • v. Most mothers recover from postnatal depression, but it may set the stage for ongoing problems affecting the child’s behavior
    • vi. Problems exhibited may involve genes inherited from depression-prone mothers and/or stressful experiences
• D. The Partner’s Experience (p. 93)
• 1. Western society fathers historically excluded from birth process
  • a. Today, many men prepare for childbirth
    • i. Take prenatal classes
    • ii. Are present at birth
• b. Birth of their child tends to be a significant event in the life of most men
  • i. Experience both positive and negative emotions in anticipation of becoming a parent
  • ii. Are anxious during pregnancy and birth
  • iii. Experience some of the same physiological symptoms as mothers
• c. Many men find labor period to be more work than expected and feel scared or unprepared
  

IV. The Neonatal Environment (p. 95)

• A. Neonatal environment—emphasis on events in first months after birth (p. 95)
  • 1. Brazelton Neonatal Behavioral Assessment—newborn assessment scale
    • a. Assesses reflexes and responses to 26 situations
    • b. Test used to teach parents how to be responsive to infants
• B. Identifying At-Risk Newborns (p. 96)
  • 1. At-risk status may be due to genetic, prenatal hazards, or perinatal damage
  • 2. Apgar test—used to assess newborn status
    • a. Assesses factors of heart rate, color, muscle tone, respiration, and reflexes
    • b. Simple five-minute test with score of 0, 1, or 2 for each factor
    • c. Apgar score of 7 to 10 good, 6 to 5 ok, less than 4 low score and at-risk status
      • i. Low score symptoms include not breathing or limp
      • ii. Low score infants immediately receive medical attention (different postnatal environment)
    • d. Low-birth-weight (LBW) babies
    • i. Associated with the age of the mother, lower socioeconomic status, race, prior premature deliveries, tobacco or alcohol use, stress, pregnancy with multiple fetuses, infections, and high blood pressure
• C. Risk and Resilience (p. 99)
  • 1. Resilience—ability to get back on course of normal development
  • 2. Protective factors help children overcome disadvantage
    • a. Personal resources—intellectual, social, and communication traits that help one cope
    • b. Supportive postnatal environment—social support from environment matters throughout life

Back to Main Page

Back to TAMUT Start Here Page