Prenatal Development
definition
development
sequence of age-related changes that occur as a person progresses from conception to death
prenatal period
extends from conception to birth, usually encompassing nine months of pregnancy
Course of Prenatal Development
- Germinal Stage
first phase of prenatal development, encompassing the first 2 weeks after conception
begins
zygote is created
fertilization
within 36 hrs
rapid cell division
become multiplying cells
slowly migrates
along fallopian tube
uterine cavity
about 7th day
cell mass
implant itself in uterine wall
about a week
during implantation
placenta form
structure that allow oxygen & nutrients to pass into the fetus from the mother bloodstream and bodily waste to pass out to the mother
critical exchange
across thin membranes
block passage of blood cells
keep maternal & fetal bloodstream separate
- Embryonic Stage
second stage of prenatal development, lasting from 2 weeks till end of 2nd month
most vital organs & bodily systems begin to form
embryo
spine, heart & brain
emerge gradually
cell division
more specialized
arms, legs etc.
discernible
period of great vulnerability
anything interferes normal development
effects devastating
most miscarriages occur here
most structural birth defects occur here
- Fetal Stage
third stage of prenatal development, lasting from 2 months through birth
first 2 months
rapid body growth
eg. muscles & bones
fetus
capable of physical movements
skeletal structures harden
organs continue to grow
gradually begin to function
final 3 months
brain cells multipy
brisk pace
layer of fat deposited under skin
provide insulation
respiratory & digestive system mature
between 23 & 25 weeks
threshold of viability
age which baby can survive in event of premature birth
Environment Factors
Nutrition
maternal nutrition
important
developing fetus needs variety of essential nutrients
severe maternal malnutrition
↑ risk of birth complications
neurological deficits for newborn
moderate malnutrition
hard to gauge
often confounded
other risk factors
associated with poverty
Stress & Emotion
consume balanced diet
maternal emotions in rxn to stressful events
impact on prenatal development
↑ levels of prenatal stress
↑ stillbirths
impaired immune response
↑ vulnerability to infectious disease
disrupt hormonal balance
foster healthy development
Drug Use
most drugs consumed
slip through membranes of placenta
"recreational drugs"
harmful
esp. sedatives etc.
born addicted to narcotics
tobacco use
problematic
↑ risk of miscarriage etc.
Alcohol Consumption
heavy drinking
hazardous
fetal alcohol syndrome
collection of congenital (inborn) problems associated with excessive alcohol use during pregnancy
most common
intellectual disability
moderate drinking
↑ risk of deficits in IQ
motor skills
Maternal Illness
diseases
measles etc
hazardous
nature of damage
depend on when it is contracted
HIV virus
cause AIDS
transmitted
thru placenta / during delivery / breastfeeding
Environmental Toxins
exposure to air pollution
impairments in cognitive development
age 5
↑ obesity
age 7
exposure to chemicals
flame-retardant materials
slower mental & physical development
up thru age 6
Fetal Origins of Adult Disease
events during prenatal development
"program" fetal brain
influence person's vulnerability
types of illness
eg. prenatal malnutrition ⇌ vulnerability to schizophrenia
low birth weight ⇌ ↑ risk of heart disease