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Janet Belsky’s
Experiencing the Lifespan, 2e
Chapter 2:
Prenatal Development,
Pregnancy, and Birth
Meredyth Fellows, West Chester University of PA
Fertilization:
The Reproductive Systems
Female Reproductive
Structures
�Uterus
�Endometrium
�Cervix (neck of uterus)
�Fallopian tubes
�Ovaries
�Ovareside here
�Ova contain mother’s
genetic material
Reproductive Systems
Male Reproductive
Structures
�Testes
(continually
manufacture
sperm)
�Penis
Process of Fertilization: Union
of Sperm and Egg
�Ovulationoccurs:
�ovum expelled from
ovary
�suctioned into fallopian
tube
�Millions of sperm travel up
fallopian tube to ovum
�Alive for 7 days
�Fertilization
�One sperm penetrates
the ovum
�Nuclei (genetic material)
of the male and female
cells combine
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Genetics: Chromosomes, DNA,
Genes
�23 chromosome pairs
contain DNA (genetic
material)
�23 single strandseach
from mother and father
�Sex chromosome=1
chromosome pair (XX
female, XY male)
�Genes
�Located on chromosomes
�Contain chemical blueprint for
manufacture of proteins
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
Stages of Prenatal Development
�Germinal
�First 14 days
�Period of Zygote
�Embryonic
�Week 3 to 8
�Period of Embryo
�Fetal
�Week 9 to Birth
�Period of Fetus
Germinal Stage: First two weeks
�Day 1 to 14, time from fertilizationto implantation
of blastocyst
�Zygotedivides once in the first 36 hours
�Every 12 -15 hours, divides again
�3 day trip down fallopian tube
�Once in the uterus, differentiates into
layers
�Zygote now called a blastocystand has
about 100 cells
�Blastocystimplants into the upper part of
the uterus
�Blood vessels proliferate to form the
placenta
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Recap: Events of the Germinal
Stage
Embryonic Stage: Weeks 3 to 8
�Fast paced forming of major organs and
body structures
�3rdweek after fertilization, circulatory
system forms and heart beats
�Neural tube forms—begins to
differentiate into the brain and spinal cord
�Arm and leg buds appear and elongate,
the heart begins to pump
�Outlines of eyes and ears 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.
Weeks 3, 4, and 9 of
Embryonic Stage
�Note proximodistaland cephalocaudal
trends
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 tube, reach their
staging area and begin to
differentiate ( see
illustration)
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Fetal Stage
�Age of viability22 weeks (earliest date for
survival)
�Vital that baby’s lungs are mature enough to
breathe in oxygen and expel carbon dioxide.
�By the 25thweek, viability is above 50% if
acute care is available.
�Birth weight important to health of baby
�Baby needs as much time in womb as possible
�During last two months fetus gains 5 pounds
Poised to be Born!
�Illustration shows
fetus inside the
womb late in
pregnancy.
�Notice the placenta,
amniotic sac, and
umbilical cord
Pregnancy
�Gestation Period: period of pregnancy, 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 mayproduce fainting,
headaches, fatigue, tender breasts and morning
sickness
�Miscarriages (spontaneous abortions) are more
prevalent at this time
�Roughly 1 in 10 pregnancies ends in miscarriage
�Women in their late 30’s, miscarriage rate increases to 1 in 5
Pregnancy: Second Trimester
�Physically may feel much better
�Need for maternity clothes
�Quickeningoccurs (first indication of
the fetus moving)
�Feelings of attachmentmay begin
�A strong sense of attachment predicts
positive bonding after birth (although
attachment can happen at any time!)
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Pregnancy: Third Trimester
�Physical Symptoms and Emotional
States
�Leg cramps, backaches, anxiety, numbness in
lower limbs, heartburn, insomnia
�Irregular uterine contractions as baby sinks into
the birth canal
�Anxiety may begin as the focus shifts while
awaiting birth
Exploring the Pregnant Brain
�Recent research suggests:
�Pregnant women, no matter what the initial stress
levels, may experience less anxietyduring late
pregnancy.
�Research suggests that a woman’s physiology may
become biologically less reactive to stress prior to the
birth.
�Women whose stress levels remained high were more
likely to have premature births.
“Baby Brain”
�“Baby Brain”
�An expectant mother may feel as if she is
experiencing mental fog; thinking processes may
become hazy.
�Research with rats who have given birth shows:
�Aftergiving birth, pre-birth cognitive deficits more
than reverse.
�Changes seem to permanently pump up the
neurons in the memory centers of the brain.
�Better performance on memory and learning
tasks
�Research needed to show similar changes in humans
Pregnancy Is Not A Solo Act
�What forces turn the experience of pregnancy
into a period of distress?
�Low SESplaces women at risk of feeling
demoralized and depressed
�Low SES contributes to lack of access to prenatal
care, proper foods, and often, social support
�“Being loved” is the main force predicting
happy pregnancy. (social support)
�Dads also may experience strong emotions.
�They too may feel worried about this life change.
�Social support necessary
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Threats to the Developing
Baby: Category 1: Teratogens
�Teratogens: substances that may
cross the placenta to harm the
developing embryo or fetus
�Examples:
�Medications –Thalidomide
�Diseases –Rubella
�Social Drugs -Alcohol,
Nicotine, Cocaine
�Environment-Pesticides,
Radiation
�Stress –hormones and
effects on unborn baby
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
�2ndand 3rdtrimester: risk of developmental
disorders
�Operate in a dose-response fashion (threshold level)
�Exert damage unpredictably
�Teratogens may also exert influence long after exposure
(e.g. DES, diethylstilbestrol)
Teratogens: Nicotine and
Alcohol
�Nicotine:
�Constricts blood vessels
�Increases risk of smaller
than normal and less
healthy newborn
�Alcohol:
�Excessive consumption
contributes to chance of
Fetal Alcohol Syndrome
Measurement Issues: How
much 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
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Threats from Within:
Chromosomal Disorders
�Chromosomes: human
complement is 46 (23 pairs)
�If developing baby is missing
or has an extra
chromosome, embryo may
miscarry
�When an extra chromosome
does occur:
�Down syndrome –
trisomy 21 (extra
chromosome or piece
copy to adhere to
chromosome 21)
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
Down Syndrome continued
�At risk for heart defects and childhood
leukemia
�Mild to moderate mental retardation
�Shortened life-span
�Average life expectancy, 58!
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 genedisordersoccur due to a flaw in a
particular gene.
�Three modes of inheritance:
�Dominant
�Recessive
�Sex-Linked
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Genetic Disorders
�Dominantdisorders
�A person who inherits one copy of
the gene alwaysgets the disease.
�If oneparent has the genetic
disease, each child has a 50/50
chanceof 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.
Genetic Disorders: Sex-linked
single-gene disorders
�Sex-Linked single-
gene disorder
�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
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
Prenatal Tests
�Ultrasound
�Commonly used to date the
pregnancy and chart the fetus’s
growth, but it can also reveal
structural abnormalities.
�Chorionic Villus Sampling
�During 1sttrimester, remove
piece of developing placenta
�Test for genetic and
chromosomal conditions.
�Risks:
�5% risk of miscarriage
�Chance of limb
impairment
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Prenatal Testing
�Amniocentesis
�2ndtrimester procedure, typically week 14
�Remove cells from amniotic fluid and test
for genetic and chromosomal conditions
�Risk
�Miscarriage
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 involved
�Emotional
consequences
�Anxiety, guilt, jealousy
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
�put into petri dish along with partner’s sperm
�Developing cell mass is inserted into the woman’s
uterus with the hope of implantation into uterine
wall
Birth!
�Stage 1:Dilation
and Effacement
�Stage 2:Birth
�Stage 3:The
Expulsion of the
Placenta
Some threats during birth
include: baby inbreech
position, cervix not fully
dilating, difficult position
of umbilical cord
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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
�Procedure common in some countries
�Used in the U.S. if complications occur
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
The Newborn
�Apgar Scale: first test immediately after birth
�Rated 0 to 2 for each category at one minute and
five 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
Threats to Development
�Low Birth Weight (LBW)
�Body weight of less than 5 ½ lbs.
�Arrived too early or did not grow in womb
�Very low birth weight
�Body weight of less than 3 ¼ lbs.
�Often very premature and rushed to NICU
(neonatal intensive care unit)
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Infant Mortality
�Infant mortality is an overall
barometer of a nation’s status.
�Countries vary greatly in their
infant mortality rates—with
developing countries doing far
worse.
�The U.S. ranks a humiliating 41st
in the world.
�One reason is our nation’s high
income inequalities, and
inadequate access to good
prenatal care
�SOCIOECONOMIC STATUS AFFECTS
OUR LIFESPAN JOURNEY FROM the
FIRST MOMENTS OF LIFE.