Transcript Invitation to the Life Span by Kathleen Stassen Berger

The Developing Person
Through the Life Span 8e
by Kathleen Stassen Berger
Chapter 4 – Prenatal
Development and Birth
PowerPoint Slides developed by
Martin Wolfger and Michael James
Ivy Tech Community College-Bloomington
Reviewed by Raquel Henry
Lone Star College, Kingwood
Prenatal Growth
Three main periods of prenatal development
1. Germinal Period (1st two weeks after
conception): rapid cell division and beginning of
cell differentiation
2. Embryonic Period (3rd through 8th week): basic
forms of all body structures develop
3. Fetal Period (9th week until birth): fetus grows
in size and matures in functioning
The Germinal Period
• Zygote begins duplication and division within
hours of conception
• Development of the placenta
– Organ that surrounds the developing embryo
– Sustains life via the umbilical chord
• Implantation (about 10 days after conception)
– Developing organism burrows into the placenta that
lines the uterus
The Germinal Period
The Embryonic Period
Embryo
• 3rd through the 8th week after conception
• Begins when the primitive streak appears down the
middle of the cell mass
• Primitive streak becomes the neural tube and later
the brain and spinal column
• Eyes, ears, nose, and mouth form
• Heart begins to pulsate
• Extremities develop and webbed fingers and toes
separate
The Embryonic Period
The Fetal Period
Fetus
• 9th week after conception until birth
• Genitals form and sex hormones
cause differences brain organization
• Cephalocaudal and proximodistal
growth
• Heartbeat detectable via stethoscope
• Cortex is not fully mature at birth
• Brain at birth is biggest part of baby
The Fetal Period
Age of viability
• Age at which a preterm
newborn may survive outside
the womb with medical care
• About 22 weeks after
conception
• Brain is able to regulate basic
body functions
• Chances of survival increase
with each day after the 22week mark
The Fetal Period
Birth
• Fetal brain signals the release of hormones to
trigger the mother’s uterine muscles
• Labor begins
– Average duration for first babies: 12 hours
– Quicker labor for later babies
• Apgar scale
– Quick assessment of newborn’s heart rate, breathing,
muscle tone, color, and reflexes
– Completed twice (1 minute and 5 minutes after birth)
– Score of 0, 1, or 2 in each category
– Desired score: 7 (total) or above
A Normal, Uncomplicated Birth
Birth
Medical Assistance
Cesarean Section (c-section)
• Surgical birth
• Fetus can be removed quickly
• Rates and reasons for c-sections vary
– Lower rates in poorer countries
– Higher rates in richer countries
– 1/3 of births in the United States
• Less trauma for the newborn but slower
recovery for the mother
• Subsequent cesarean deliveries may be
necessary
Newborn Survival
• Infant mortality has decreased due to better
medical care
– 1900: 5%
– Today: <1 in 200
• Childbirth has become safer for mothers
– Death rate in poorest nations: 1 in 20 women
• Excessive medical care also has disadvantages
– Increase in unnecessary c-sections is associated with
higher rate of low-birth weight babies
Traditional and Modern Birthing
Practices
• Home births
• Hospital births
• Doula
– Woman who helps with labor, delivery, breastfeeding, and newborn care
– May be related to lower rate of cesarean
sections
Harmful Substances
• Teratogens
– Substances and conditions that can impair prenatal
development and result in birth defects or even death
– Not all teratogens can be avoided
– Structural abnormalities are obvious at birth
• Behavioral teratogens
– Affect the child’s developing brain
• Developmental retardation, hyperactivity, and learning
disabilities
– Effects do not become evident for months or years
Risk Analysis
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•
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Knowing which risks are worth taking
How to minimize chance of harm
Teratology: science of risk analysis
Threshold effect: when a teratogen is
harmless in small doses but becomes
harmful at a certain level (threshold)
Applying the Research
• Fetal alcohol
syndrome (FAS)
– A cluster of birth
defects including
abnormal facial
characteristics, slow
physical growth, and
retarded mental
development
– May occur in the child
of a woman who drinks
alcohol while pregnant
Low Birthweight
• Low birthweight (LBW)
– Less than 2,500 grams (5½ pounds) at birth
– United States
• Steady increase in LBW over the past 25 years
• 8% of newborns are seriously underweight
• More susceptible to teratogens, higher birth risks, lower
survival rate
• Very low birthweight (VLBW)
– Under 1,500 grams (3 pounds, 5 ounces) at birth
• Extremely low birthweight (ELBW)
– Under 1,000 grams (2 pounds, 3 ounces) at birth
Preterm or Slow Growing?
• Preterm
– Birth that occurs at 35 or fewer weeks after
conception
– Usually associated with low birthweight
• Small for gestational age (SGA)
– Birthweight is significantly lower than
expected, given the time since conception
– Suggests impairment throughout prenatal
development and serious problems
Complications During Birth
• Cerebral palsy:
-damage to the brain’s motor centers
-speech and/or muscles are impaired
• Anoxia:
-lack of oxygen
-over time can cause brain damage or
death
The Newborn
• Brazelton Neonatal Behavioral
Assessment Scale (NBAS)
– A test that measures responsiveness
– records 46 behaviors, including 20 reflexes
Moving and Perceiving
The Newborn
• The first movements are not skills but
reflexes, involuntary responses to a
particular stimulus.
The Newborn
Some reflexes aid survival
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•
•
•
•
•
•
breathing
thrashing
shivering
sucking
rooting
swallowing
spitting up
The Newborn
Other reflexes signify normal functioning:
• Babinski reflex. When feet are stroked, their toes fan
upward.
• Stepping reflex. When held upright with feet touching a
flat surface, infants move their legs as if to walk.
• Swimming reflex. When laid horizontally on their
stomachs, infants stretch out their arms and legs.
• Palmar grasping reflex. When something touches
infants’ palms, they grip it tightly.
• Moro reflex. When someone startles them, infants fling
their arms outward and then bring them together on
their chests, as if to hold on to something, while crying
with wide-open eyes.
The Father’s Role
• Supportive father helps mother stay healthy
• Father can decrease or increase mother’s
stress (affects fetus)
• Most fathers are helpful to their pregnant
wives
• Two way street: Pregnant mothers should
support, involve, and encourage fathers
The Father’s Role
• Couvade: symptoms of pregnancy and
birth experienced by fathers
• Parental alliance:
– cooperation between a mother and a father
based on their mutual commitment to their
children
– the parents support each other in their shared
parental roles.
Postpartum Depression
• Sadness and inadequacy felt by 8-15% of new
mothers in the days and weeks after giving birth
• Symptoms range from baby blues to postpartum
psychosis
• baby care feels burdensome and thoughts of
mistreating the infant may exist
• Paternal involvement can have beneficial effect
– Some fathers are depressed themselves
• Causes for Postpartum Depression vary
Bonding
Parent-Infant Bond
• The strong, loving connection that forms as
parents hold, examine, and feed the newborn
• Early skin-to-skin contact is not essential
• Cross-fostering in monkeys
– Newborns are removed from their mothers and
raised by another female or male
– Strong and beneficial relationship sometimes
develops
Bonding
• Birth complications can have lingering impact on
later life
• Mothers and fathers should help with early
caregiving if newborn must stay in the hospital
• Kangaroo care
– Child-care technique in which the mother of a LBW
infant holds the baby between her breasts
– Allows baby to hear mother’s heartbeat and feel her
body heat
– Research confirms beneficial effects