Kathleen Stassen Berger
Part I
Chapter Four
Prenatal Development and Birth
From Zygote to Newborn
Risk Reduction
The Birth Process
Prepared by Madeleine Lacefield
Tattoon, M.A.
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Prenatal Development and Birth
• The majority of newborns are male
(52%), and more are Chinese (30%)…
yet every baby is unique… every area
of development is directly relevant to
the 150 million babies born in the world
every year… there are generalities and
variation… but expect to be awed by the
miracle of birth.
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From Zygote to Newborn
• Prenatal development is divided into three
main periods
– germinal Period (0-2 weeks)
– embryonic Period (3-8 weeks)
– fetal Period (9 weeks-birth)
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From Zygote to Newborn
• Germinal: The First 14 Days
• Conception occurs in fallopian tubes
• Cell differentiation and multiplication
• 42% of conceptions successfully implant in uterus
– blastocyst
• when cells take on distinct characteristics and gravitate toward
particular positions, the entire cell mass (still very fragile and tiny)
– placenta
• the organ that surrounds the developing embryo and fetus,
sustaining life via the umbilical cord…attached to the wall of the
uterus
– Implantation
• the process, beginning about 10 days after conception, which the
developing organism burrows into the placenta that lines the uterus,
where it can be nourished and protected as it continues to develop.
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From Zygote to Newborn
• Embryo: from the third through the eighth week
– embryonic period (3-8 weeks)
• major organs develop
• at eight weeks, organism is less than 2˝
long
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From Zygote to Newborn
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From Zygote to Newborn
• Fetus: From the Ninth Week Until
Birth
– Fetal Period (9 weeks-birth)
• Sex organs develop
• Brain development is significant
• Age of viability occurs around 22 weeks
– fetus
• a developing organism from the ninth week
after conception until birth
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From Zygote to Newborn
• The Third Month
– the fetus has all its body parts
– weighs approximately 3 ounces, about 3
inches long
– growth is rapid
– fetus is too small survive outside of the
womb
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From Zygote to Newborn
• The Middle Three Months: Preparing to Survive
– in the fourth, fifth and sixth
months the heartbeat
becomes stronger
– the cardiovascular system
more active
– the brain increases about six
times in size
• age of viability
– twenty-two weeks after
conception a fetus can survive
outside the mother’s uterus if
specialized medical care is
available
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From Zygote to Newborn
• The Final Three Months: From Viability to Full
Term
– Viability
• life outside the womb is possible
• born in the seventh month requires intensive
hospital care and life-support systems
• difference between preterm and newborn is the
maturation of neurological, respiratory,
cardiovascular systems
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Risk Reduction
• toxins, illnesses and experiences can harm a
developing person before birth
– teratology
• a science of risk analysis, the study of birth defects
– teratogens
• Agents and conditions that can harm the prenatal brain,
impairing the future child’s intellectual and emotional
functioning
– behavioral teratogens
• Agents and conditions that can harm the prenatal brain,
impairing the future child’s intellectual and emotional
functioning
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Risk Reduction
• Determining Risk
– risk analysis
• the science of weighting the potential effects of a
particular event, substance, or experience to
determine the likelihood of harm
• Timing of Exposure
– critical period
• In prenatal development, the time when a
particular organ or other body part of the embryo
or fetus is most susceptible to damage by
teratogens
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Risk Reduction
• Amount of Exposure
– Threshold effect
• a situation in which a certain teratogen is
relatively harmless in small doses but
becomes harmful once exposure reaches a
certain level (the threshold)
– Interaction effect
• the result of a combination of teratogens.
Sometimes risk is greatly magnified when
an embryo or fetus is exposed to more than
one teratogen at the same time
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Genetic Vulnerability
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Risk Reduction
• Protective Measures
• Benefits of Prenatal Care
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The Birth Process
• The Newborn’s First Minutes
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The Birth Process
• The Newborn’s First Minutes
– Apgar scale
• a quick assessment of a newborn’s body
functioning.
– color
– heart rate
– reflexes
– muscle tone
– respiratory effort
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The Birth Process
• Variations
– medical Intervention
• cesarean section
– fetus is removed through incisions in the mother’s
abdomen and uterus
• birth complications
– includes anything in the newborn, the mother, or
the birth process itself that requires special
medical attention
– anoxia
• a lack of oxygen that, if prolonged during
birth, can cause brain damage or death to
the baby
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The Birth Process
• Low Birthweight (LBW)
– the average weight of a newborn is 7½ lbs.
• LBW is considered less than 5½ lbs.
• preterm is less than 35 weeks
– lifestyle choices
• e.g., cigarette smoking accounts for 25% of
LBW births worldwide!
– maternal malnutrition
– multiple births
– prescription drugs
– unknown causes
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The Birth Process
• Social Support
– Mother, Father, and a Good Start
– Help from fathers
• parental alliance – cooperation between a mother and a
father based on their mutual communication to their
children… the parents agree to support each other in their
shared parental roles
• Postpartum Depression
– 8-15% of women experience postpartum depression, a
sense of inadequacy and sadness after birth.
– includes irritability, sleep and eating disruptions, sadness,
feeling overwhelmed and inadequate as a mom, no interest
or overly worried about baby.
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