1. Chapter 4: Prenatal development, birth, and newborns’ readiness for life.
Dr. Pelaez

2. From conception to birth
Prenatal development is divided into 3 major phases:
Germinal period
Embryonic period
Fetal period

3. Germinal Period From conception to implantation (about 14 days).
Zygote moves toward uterus through fallopian tube
Implantation occurs
Support system develops (4 structures)
Implantation: blastocyst forms tendrils which attach to the uterine wall
Support System includes amnion (water like membrane to regulate temperature and cushion), chorion, placenta, umbilical cord.

4. Embryonic period Lasts from week 3 to week 8.
Neural tube development begins.
Heart begins to beat
Grows about 1/30 inches per day.
External body structures form (ears, limbs, eyes)
Neural tube: spinal cord develops from ectoderm and becomes the CNS.
ectoderm develops into nervous system, skin & hair
Mesoderm develops into muscle, bone & circulatory system
Endoderm develops into digestive system, lungs, and other vital organs

5. Fetal period Lasts from week 9 to term.
By end of month 3, sex can be detected on ultrasound
Neural and muscular systems continue to develop
By second trimester (month 5-6), covered by vernix & lanugo (substance that protects fetal skin & fine hair which helps vernix to stick to body).
Third trimester (weeks 25-38) involve rapid growth and maturity of all organ systems.
Age of viability: a point between the 22-28th weeks in which survival outside the uterus may be possible.

6. Teratogens
External agents such as viruses, drugs, and radiation that can be harmful to developing embryo or fetus.
Sensitive periods
Long-term effects depend on the quality of postnatal environment
Sensitive periods: each organ has a time when it is highly susceptible to teratogenic agents.
Example: 69h week of development is a sensitive period for external genital development.

7. Maternal diseases
Diseases capable of passing through placenta and damage embryo/fetus
Rubella % of babies exposed will have birth defects.
STD’s (AIDS, herpes, syphilis).
Toxoplasmosis
Influenza
Malaria
Tuberculosis

8. Drugs
Drugs taken by mother can have harmful effects on children: (low birth weight, heart defects, brain & neurological defects, and death).
Thalidomide
Diethylstilbestrol (DES)
Alcohol
Cigarettes
Illegal, prescription, and over the counter drugs
Thalidomide: used in the 1960’s to help mothers who experienced nausea.
DES: drug prescribed in 1940’s-50’s. Later risk for abnormalities in reproductive organs, including cervical cancer
Drugs: marijuana, heroin, cocaine, amphetamines, sex hormones, vitamins, aspirin, tranquilizers.

9. Environmental hazards
Environmental hazards that may cause low birth weight, miscarriages, or genetic defects to embryo/fetus:
Radiation
Lead
Zinc
Mercury
Other harsh chemicals

10. Maternal characteristics
Maternal behavior can affect the outcome of her pregnancy
Mother’s diet
Mother’s emotional well-being
Mother’s age
Folic acid should be consumed to prevent CNS defects
Mothers should gain between pounds, ideally.
Prolonged & severe stress tends to have effects such as irritability, low weight, and irregular sleeping and feeding habits on babies.
Ideal age to bear children is between

11. Birth Process
Perinatal environment: environment surrounding birth; includes influences such as drugs given to the mother, delivery practices, and the social environment.
3 stage process:
1. first stage of labor: uterine contractions. Lasts about 3-8 hours.
2. second stage of labor: fetus moves through birth canal & emerges from mother’s body.
3. third stage of labor: expulsion of the placenta
First stage: contractions are at 10-1 minutes intervals.
Second stage: baby delivery

12. Three stages of child birth.

13. Social environment at birth
First hours are a sensitive period of emotional bonding.
Postpartum depression may inhibit emotional bonding.
Early father-infant interactions may make fathers feel more a part of the family.
If experiencing post partum depression, seek professional help. Otherwise, infant attachment may be insecure.

14. Assessing the baby’s condition
Apgar test: assess newborn heart rate, color, respiration, muscle tone, and reflexes.
Neonatal Behavioral Scale (NBAS): assess neonate’s neurological integrity and responsiveness to environmental stimuli.
NBAS administered a few days after birth
Assess 20 reflexes.
Low scores may indicate brain damage or other neurological problems
NBAS: ideally,
heart rate :over 100bpm.
Respiratory effort: good, baby is crying
Muscle tone: strong & Active motion
Color: completely pink
Reflex: vigorous cries, coughs, sneezes

15. Birth complications Anoxia Premature delivery Low birth weight
Oxygen deprivation
Breech position
Rh factor
Premature delivery
Preterm: born 3 weeks or more before term.
Small for date babies
Low birth weight
Small for date: slow growth
Under 5 lbs
May experience respiratory distress syndrome
Rh factor: blood protein that when present in fetus, but not mother, can cause antibodies to be produced which may attack the red blood cells in subsequent fetuses who have the protein in their blood.
Respiratory distress syndrome: irregular breathing due to insufficient surfactin.
Medications can cross placenta and make the baby lethargic or inattentive

16. Readiness for life Healthy newborns display a number of reflexes.
Survival reflexes: breathing, sucking & swallowing
Primitive reflexes (disappear during first year of life): babinksi reflex, swimming, stepping reflex
Babinksi: fanning/curling toes when foot is stroked

17. Readiness for life continued
Infant states.
Regular sleep: 8-9 hours/day
Irregular sleep: 8-9 hours/day
Drowsiness: ½-3 hours/day
Alert inactivity: 2-3 hours/day
Alert activity: 1-3 hours/day
Crying: 1-3 hours/day
Infants spend have of their sleeping hours in REM sleep.
SIDS: leading cause of death of infants within first year of life

18. Reflexes in full term infants
Table 4.6
Pg. 135