Fetal Brain Development
Five months after conception – 4% of adult weight
At birth – about 25% of adult weight
At four years – about 80% of adult weight
Brain stem and midbrain – fairly well established at birth
-
reflexes
-
biological functions
Cortical areas – associated with sensation, motor responses, thinking,
planning, etc.
-
neural changes continue well after birth
Neuron Proliferation
-
begins near end of first month
-
production of new nerve cells
-
produced in the neural tube
-
over 100 billion young neurons by birth
(many by the sixth month)
Neuron Migration
-
neurons move from the neural tube to other locations in two
ways
1. in the hypothalamus, brain stem & cerebellum, older neurons
are pushed out
2. inside-out pattern: neurons migrate to other regions
-
pass through levels of older nerons
-
young neurons move along fibers of glial cells
-
occurs in waves, esp. 7th and 11th week
Neuron Differentiation
-
neurons enlarge
-
form synapses with other neurons
-
external stimulation plays major role in differentiation
establishes connections among neurons
maintaining and strengthening of connections
huge rise in synapses in first months after bith
then pruning begins
Childbirth
Traditional birth
"Modern" birth
A return to traditional birth?
Hospital or home?
Hospital "birth rooms"
Midwife
Doula
Three stages of labor
Stage one: dilation of the cervix
entering the birth canal
Stage two: moving through the birth canal
the birth
Stage three: delivering the placenta
The Newborn (Neonate)
Newborns look strange!
Born a bit early - covered with vernix, a white waxy substance
that keeps water off the skin
Born a bit late - red and wrinkly
Born very early - covered with hair (lanugo) to hold the vernix
in place
Skull may be misshapen
Skin may be uneven in color
Reflexes of Newborns
Maintaining oxygen supply:
- breathing
- sneezes
- hiccups
- thrashing
Maintaining body temperature:
- crying
- shivering
- tucking legs in close
Feeding:
- sucking
- rooting
- swallowing
- crying
- spitting up
Other Reflexes:
- grasping
- stepping
- swimming
- Babinski
- Moro
Most reflexes disappear during the first few months, as purposeful
behavior develops.
Infant Behaviors
Sleeping and waking:
- on average, newborns sleep 16 - 18 hours a day, half in REM
sleep
- amount of sleep may vary widely
Feeding:
- depends on the infant
- depends on "scheduling"
Crying:
- signals discomfort, e.g., hunger or pain
- reaction to sudden changes
- amount of crying may vary widely
Individual differences for sleeping and fussing tend to be stable,
suggesting these behaviors may
Sudden Infant Death Syndrome (SIDS)
- 3rd leading cause of death in US and most western countries
- No warning
- Most frequent between 2 and 4 months, when automatic respiratory
reflexes begin to be supplemented by voluntary breathing
Risk Factors: - sleeping on stomach (back to sleep movement)
-
soft bedding
exposure to cigarette smoke
colder months
overheating
having a cold
lower SES neighborhoods
being male