1. Prenatal Development, Pregnancy, and Birth
Chapter 2
Prenatal
Development, Pregnancy, and Birth

2. Female reproductive system
Uterus
Fallopian tubes
Ovaries
Ova are in the
ovaries and
contain mother’s
chromosomes

3. Male reproductive system
Testes continually
manufacture
sperm
Penis

4. Fertilization Ovulation ovum ejected from Ovary and moves into
fallopian tube
Millions of sperm travel up fallopian tube to the ovum (they live 7 days)
Fertilization
Only one sperm penetrates ovum
Genetic material of male and female combine

5. Genetics
23 chromosome pairs
(contain DNA)
23 each from mother and father
Sex chromosomes join in only one pair (XX for female child, XY male)
Genes are on chromosomes, act like blueprint of the developing individual

6. Prenatal Development Proximodistal Cephalocaudal Mass to specific
Growth from mid-inside out
Cephalocaudal
Growth from head to foot (tail)
Mass to specific
Large structures, then fine features
Large movement, then fine movement

7. Prenatal Stages Germinal (zygote) Embryonic Fetal First 14 days
3rd to 8th week
Fetal
9th week to birth

8. Embryonic Stage
Proximodistal and
cephalocaudal

9. Fetal Stage
Age of viability 22 weeks, earliest date for survival outside the placenta
Birth weight is important
Baby needs as much time in the womb as possible – in last two months the fetus gains 5 pounds

10. Teratogens
Substances that cross the placenta and harm the embryo or fetus:
Medication (thalidomide)
Disease (Rubella)
Social drugs (alcohol, nicotine,
marihuana, cocaine)
Environmental (pesticides,
radiation)
Stress (effects of hormones)

11. Effects of teratogens Most damage during sensitive periods
Structural damage in embryonic period
Can affect brain throughout pregnancy
Developmental disorder risk highest in 2nd to 3rd trimester
Dose-response effect (threshold level)
May act long after exposure

12. Effects of nicotine and alcohol
Constricts blood vessels
Increases risk of smaller less healthy babies
Alcoholism
Risks Fetal Alcohol Syndrome (FAS).
Know the symptoms!

13. Chromosomal Disorders
46 chromosomes interact in 23 pairs
If a chromosome is missing or extra the embryo may miscarry
An extra chromosome 21 causes Down syndrome (trisomy 21). Was called “Mongolism!“ and
“Mongoloid idiot”

14. Single-gene disorders
Genes are on chromosomes and determine specific traits
Most traits depend on many genes but single gene disorders occur when there is a defect in only one gene.
Three heritability modes:
Dominant or recessive gene
Sex-linked gene

15. Genetic Counseling Genetic Counselors Genetic Testing
Counsel couples about their own or child’s risk of genetic disorders
Give advice about available treatments
Help couples make a decision
Genetic Testing
Blood test determines whether a person carries a gene for a genetic disorder

16. Prenatal Tests Ultrasound
Dates pregnancy and charts fetus growth but can reveal structural abnormalities.
Chorionic Villus Sampling
During 1st trimester, piece of developing placenta tested
for genetic conditions.
Amniocentesis
2nd trimester, tests amniotic fluid for genetic conditions. Has some miscarriage risk.

17. Birthing Stage 1: Dilation and effacement (crowning) Stage 2: Birth
Stage 3: Expulsion of placenta
Threats: breech position, cervix not fully dilating, difficult position of umbilical cord

18. Birth Options Natural childbirth Cesarean
No medication, help of midwife or doula
Bradley, natural, no medication
Lamaze pain management
Sometimes medical intervention is needed.
Cesarean
More common in some countries
Used if there are complications

19. The neonate (newborn)
Apgar Scale: first test after birth, scored 0, 1, 2 in five categories, at one and five minutes after birth. Over 7 is healthy.
Skin color
Muscle Tone
Respiration
Heart Rate
Reflex Response

20. Threats to Development
Low Birth Weight
Body weight less than 5½ lbs.
Arrived too early or delayed growth
Very low birth weight
Weighs less than 3¼ lbs.
If very premature, treated in neonatal intensive care unit

21. Infant Mortality Measure of a nation’s overall health care
U.S. ranks 41st. Some reasons are poverty and inadequate access to prenatal care
Socioeconomic status (SES) affects healthcare across the life span.