1. Janet Belsky’s Experiencing the Lifespan, 3e
Chapter 2:
Prenatal Development, Pregnancy, and Birth
Meredyth Fellows, West Chester University of PA

2. Fertilization: The Reproductive Systems
Female Reproductive Structures
Uterus
Endometrium
Cervix (neck of uterus)
Fallopian tubes
Ovaries
Ova reside here
Ova contain mother’s genetic material

3. Reproductive Systems Male Reproductive Structures
Testes (continually manufacture sperm)
Penis

4. Process of Fertilization: Union of Sperm and Egg
Ovulation occurs:
ovum expelled from ovary
suctioned into fallopian tube
Millions of sperm travel up fallopian tube to ovum
Fertilization
One sperm penetrates the ovum.
Nuclei (genetic material) of the male and female cells combine.

5. Genetics: Chromosomes, DNA, Genes
Located in the nucleus of every cell, a threadlike strand of DNA, which carries the genes that transmit genetic information
DNA (deoxyribonucleic acid)
Material that makes up genes, which bear our hereditary characteristics
Gene
A segment of DNA that contains a chemical blueprint for manufacturing a particular protein

6. Genetics: Chromosomes, DNA, Genes
23 chromosome pairs contain DNA (genetic material)
23 single strands each from mother and father
Sex chromosome = 1 chromosome pair (XX female, XY male)
KARYOTYPE

7. Stages of Prenatal Development
Germinal
First 14 days, from fertilization to implantation
Period of Zygote
Embryonic
Week 3 to 8
Period of Embryo
Fetal
Week 9 to Birth
Period of Fetus

8. Germinal Stage, first two weeks: from zygote to blastocyst
Zygote (fertilized ovum)
In the first 36 hours, zygote divides once
Divides again every hours
Travels down fallopian tube for 3 days
Once in the uterus, differentiates into layers— zygote is identified as a blastocyst and has roughly 100 cells
Blastocyst implants into the upper part of the uterus
Blood vessels proliferate to form the placenta
BLASTOCYST

9. Embryonic Stage: Weeks 3 to 8
Fast paced; all major organs constructed
3rd week, circulatory system forms and heart beats
20 to 24 days neural tube forms—differentiates into brain and spinal cord
Day 26, arm buds form
Day 27, leg buds appear
Feet, elbows, wrists, and fingers begin to appear.
By week 8, the embryo is 1.5 inches long.
The internal organs are in place and embryo begins to look human.

10. Principles of Prenatal Development
Proximodistal
Growth from middle to outside
Cephalocaudal
Growth from head to tail (feet)
Mass to Specific
Large structures appear before finer details.
Large movements appear before finer movements.

11. Weeks 3, 4, and 9 of Embryonic Stage
Note proximodistal and cephalocaudal trends
Week 3
Week 4
Week 9

12. Fetal Stage: Week 9 to Birth
Baby grows dramatically:
Body structures are refined.
Building blocks of the brain are fully assembled.
Neurons ascend to the top of the neural tube, reach their staging area, and begin to differentiate.
Climbing Neurons

13. Fetal Stage
Age of viability is 22 weeks (earliest date for possibility of survival).
Vital that baby’s lungs are mature enough to breathe in oxygen and to expel carbon dioxide.
By the 25th week, viability is above 50% if acute care is available.
Birth weight is important to health of baby.
Baby needs as much time in the womb as possible.
During the last 2 months, fetus gains almost 5 pounds.

14. Poised to Be Born! Fetus positioned in the womb late in pregnancy.
Notice the placenta, amniotic sac, and umbilical cord.

15. Pregnancy Gestation Period: 267-277 days
Divided into trimesters (about 3 months each)
Important! Each woman may vary in her experience (physical and emotional) of pregnancy.
First Trimester
Following implantation of blastocyst into uterus, flood of hormones may produce fainting, headaches, fatigue, tender breasts, and morning sickness.
Progesterone; human chorionic gonadotropin (HCG)
Miscarriages (spontaneous abortions) more prevalent at this time:
Roughly 1 in 10 pregnancies ends in miscarriage.
Miscarriage rate increases to 1 in 5 for women in their late thirties.

16. Pregnancy: Second Trimester
Physically may feel much better
By week 14, uterus grows (maternity clothes!)
Quickening occurs (first indication of movement of the fetus)
Feelings of attachment may begin
A strong sense of attachment during pregnancy predicts positive bonding after birth.

17. Pregnancy: Third Trimester
Physical Symptoms and Emotional States
Leg cramps, backaches, numbness in lower limbs, heartburn, insomnia
Irregular uterine contractions as baby sinks into the birth canal
Anxious anticipation may begin as the focus shifts to the birth.

18. Pregnancy Is Not a Solo Act
Forces that may contribute the experience of distress during pregnancy
Economic concerns; low SES
places women at risk of feeling demoralized and depressed
possible lack of access to prenatal care, proper foods, and often, social support
Positive forces
Presence of a loving partner may predict a happy pregnancy.
The perception of being cared about and loved; a sense of connectedness
Husbands also may experience strong emotions.
May feel concerned about this life change
Social support necessary

19. Threats to the Developing Baby: Birth Defects Category 1: Teratogens
Teratogens: substances that may cross the placenta to harm the developing embryo or fetus
Examples:
Medications – Thalidomide
Diseases – Rubella
Recreational Drugs – Alcohol, Nicotine, Cocaine
Environment – Pesticides, Radiation
Stress – hormones and effects on unborn baby

20. Basic Teratogenic Principles
Teratogens do most damage during sensitive periods.
Four Principles
Most likely to cause structural damage during embryonic period
Can affect developing brain throughout pregnancy
2nd and 3rd trimester: risk of developmental disorders
Operate in a dose-response fashion (threshold level)
Exert damage unpredictably, depending on fetal and maternal vulnerabilities
Teratogens may also exert influence long after exposure.
DES, diethylstilbestrol
Learning disabilities

21. Teratogens: Nicotine and Alcohol
Constricts blood vessels
Increases risk of smaller- than-normal and less-healthy newborn
Alcohol:
Excessive consumption contributes to chance of Fetal Alcohol Syndrome.

22. Measurement Issues: How much exposure is too much?
Researchers experience difficulty defining exact amounts of exposure that may cause harm to the developing organism.
Self-report questionnaires may be unreliable.
Rule of thumb: Don’t smoke, drink, take drugs, and avoid exposure to teratogens.

23. In Focus: Pregnancy as a Programmer of Adult Life
Fetal Programming Research
New research discipline
Explores the impact of traumatic pregnancy events and intense stress on producing low birth weight, obesity, and long-term physical problems.
The “Hunger Winter” in 1944, Holland
Findings: Heart disease rates were higher if a fetus was exposed to the Hunger Winter.

24. Threats from Within: Chromosomal Disorders
Chromosomes: human complement is 46 (23 pairs)
Embryo may miscarry if developing baby is missing or has an extra chromosome.
e.g., Down syndrome – trisomy 21
Nondisjunction (cell division error in egg or sperm)
Causes an extra chromosome or piece of that copy to adhere to chromosome pair 21
Born with 47 chromosomes

25. Chromosomal Disorders: Down Syndrome − Trisomy 21
Risk factors: advanced maternal and paternal age (in women, ova may have chromosomal faults)
Women over 40, 1 in 100
Women over 45, 1 in 25
Symptoms: distinctive physical characteristics
Flat facial profile
Upward slant to eyes
Stocky appearance
Enlarged tongue

26. Down Syndrome continued
Risk for heart defects and childhood leukemia
Mild to moderate mental retardation
Shortened lifespan
Average life expectancy, 58!

27. Genetic Disorders: Single-Gene Disorders
Genes come in pairs – one on each chromosome – and determine specific traits
While most traits are dependent on many genes, single gene disorders occur due to a flaw in a particular gene.
Three modes of inheritance:
Dominant disorders
Recessive disorders
Sex-linked single-gene disorders

28. Genetic Disorders Dominant disorders Recessive
A person who inherits one copy of the gene always gets the disease.
If one parent has the genetic disease, each child has a 50/50 chance of inheriting the disease.
Recessive
Child gets illness by inheriting two copies of the abnormal gene that causes the disorder.
Odds of baby born to two carriers having the illness are 1 in 4.

29. Genetic Disorders: Sex-linked single-gene disorders
Illness carried on the mother’s X chromosome
Typically leaves the female offspring unaffected but has a 50/50 chance of striking each male child

31. Interventions: Sorting out the Options
First Step: Genetic Counselor
Counsels couples about their own or their children’s risk of developing genetic disorders
Advice about available treatments
Goal: permit couples to make mutual decision
Genetic Testing
Blood test: determines whether a person carries the gene for a genetic disorder

32. Prenatal Tests Ultrasound Chorionic Villus Sampling
Commonly used to date the pregnancy and chart the fetus’s growth, but it can also reveal structural abnormalities.
Chorionic Villus Sampling
During 1st trimester, remove piece of developing placenta
Test for genetic and chromosomal conditions
Risks:
5% risk of miscarriage
Chance of limb impairment

33. Prenatal Testing Amniocentesis
2nd trimester procedure, typically week 14
Remove cells from amniotic fluid and test for genetic and chromosomal conditions
Risk
Miscarriage

35. Infertility
The inability to conceive after a year of unprotected sex (includes inability to carry a child to term)
Infertility rates higher at older ages
Male and female problems equally involved

36. Interventions: Assisted Reproductive Technology
ART: treatment in which the egg is fertilized outside of the womb
In Vitro Fertilization
After woman has been given fertility drugs, eggs are harvested and put into Petri dish along with her partner’s sperm.
Developing cell mass is inserted into the woman’s uterus with the hope of implantation into the uterine wall.

37. Birth! Stage 1: Dilation and Effacement Stage 2: Birth
Stage 3: Expulsion of the Placenta
Threats during birth include:
baby in breech position
cervix not fully dilating
difficult position of umbilical cord

38. Birth Options Birth options and providers: Natural childbirth
Deliver without medication with the help of midwife or doula.
Lamaze (pain management)
Bradley (natural, non-medicated childbirth)
Sometimes, medical intervention is needed.
Cesarean Section
Procedure common in some countries
Used in the United States if complications occur

39. Medical Interventions
Episiotomy
Epidural
Electronic Fetal Monitor
Cesarean Section (C-Section)
Remove fetus manually by making incision into abdominal wall and uterus
Used when complications occur

40. The Newborn Apgar Scale: first test immediately after birth
Rated 0 to 2 for each category at 1 minute and 5 minutes after birth
Color
Muscle Tone
Respiration
Heart Rate
Reflex Response
Score over 7, healthy
Under 7, must be monitored or resuscitated and may go to NICU (neonatal intensive care unit)

41. Threats to Development
Low birth weight (LBW)
Body weight of less than 5½ lbs.
Arrived too early or did not grow in womb
Very low birth weight
Body weight of less than 3¼ lbs.
Often very premature and rushed to NICU

42. Infant Mortality: death during first year of life
Varying mortality rates among countries
Notice difference between developing and developed countries
Deaths of children under 1 year of age in 2011