Module 4 Flashcards
Prenatal Development, Birth, and the Newborn
what is preformationist?
theory of development in which prenatal life starts with a fully formed individual that gets bigger
- nativist
- false
canalization
- refers to developmental reduction in plasticity
- initially cells can become anything (stem cells); as development progresses, it’s harder to change paths
- studies with frogs: you can change a cell’s path by simply moving it- development influenced by neighboring cells
length of pregnancies
- full term at 40 weeks of pregnancy
- 40 weeks since last period, the time from conception to birth is 38 weeks
- conception happens sometime around 2 weeks after last period, but hard to now when (unless IV)
gametes
- eggs and sperm
- eggs are much bigger (largest cell) and all formed prenatally; sperm much smaller and formed throughout lifespan
haploid
- only half the genetic material found in other diploid cells
- contains 23 chromosomes vs. 23 pairs of chromosomes
fertilization and conception
- while millions of sperm are ejaculated, only 200 reach egg
- takes about 6 hours to go 6-7 inches
- when one penetrates, zona reaction occurs, blocks other sperm from entering
- sperm tail falls off and rest goes into egg
zygote
fertilized egg with 23 chromosomes from mom and 23 from dad
what develops first in prenatal development?
- cephalocaudal= head first
- basic first, then more specialized —> arm buds, then hand paddle, then fingers
- important first -> brain and heart
four major developmental processes transform a zygote into an embryo and then into fetus
- cell division = mitosis results in proliferation of cells
- cell mgiration the movement of cells from point of origin to somewhere else in embryo
- cell differentiation transforms the embryo’s unspecialized stem cells into roughly 350 different types of cells
- the selective death of certain cells (apoptosis), also enable prenatal development
- hand development
germinal period
- begins with conceptions and lasts until zygote becomes implanted in uterine wall, rapid cell division takes place
- conception - 2 weeks
- twins determined in germinal period
embryonic period
- following implantation, major development occurs in all organs and systems of body
- 3rd-8th week
- blastocyst implants into uterine wall- now an embryo!
- placenta and amniotic sac form, chemicals released to preserve pregnancy
- most sensitive period of development
- rapid cell division
- major organ forming
- most miscarriages happen here
fetal period
9th week - birth
- continued development of physical structures and rapid growth of the body
- increasing levels of behavior, sensory experience, and learning
monozygotic
- identical; inner cell mass splits
- siblings share 100% genetic material
- usually share same placenta (with own amniotic sacs)
- not always, if split happens in first 2 days —> environmental difference
- if split happens late, may share same sac- risk of umbilical cord entanglement
- very late- conjoined
dizygotic
- fraternal; 2 eggs released and fertilized by 2 diff sperm
- siblings share 50% genetic material
- i.e. no more related than non-twin sibs
- siblings share 50% genetic material
is identical/ MZ twinning hereditary?
no, but tendency for hyper-ovulation can be passed down
is fraternal/ DZ twinning hereditary?
yes
amniotic sac/ placenta
- amniotic sac: filled with amniotic fluid- protects baby, lets it move unhampered by gravity
- placenta: network of blood vessels that allows for exchanging fluids between fetus and mom
- connected to embryo by umbilical cord
- semipermeable- let good stuff in and bad stuff out
- also lets some bad stuff in
- also produces hormones (estrogen, progesterone)
the embryo layers in weeks 2-3
- top: nervous system, nails teeth, inner ear, lens of eyes, outer surface of skin
- middle: muscles, bones, circulatory system, inner layers fo skin, other intestinal organs
- bottom: digestion, lungs, urinary tract, gland
- top layer folds in on itself and becomes the neural tube
- becomes brain and spinal cord
- spina bifida results from closure errors here (taken folic acid)
4 weeks
- primitive heart begins to pump blood
- neural tube (nearly closed)
5.5-8 weeks
- facial development
- cleft palate happens here
6-8 weeks
- 3/4 inch long
- heart has 4 chambers
- fingers and toes visible
- major organs forming
- movement begins (bending spine)
9 weeks
- a fetus!
- extremely rapid brain growth
- all internal organs present
- rudimentary ears and eyes
- fingers and toes present
11 weeks
- 2.5 inches long
- fetal breathing begins
- heart has 4 chambers
- brain has major divisions
- sleep and awake states
- begin period of lower body growth
- sexual differentiation begins
- most spontaneous abortions occur before this point
sexual differentiation
- androgens (including testosterone), are produced by all fetuses, but genetically male fetus (determined entirely by sperm provided by genetic father) produces a lot more
- causes testes to develop; these eventually produce testosterone themselves
- sex chromosomes abnormalities in 1/500 births
why do sex and gender differ?
- sex is genotype
- gender is the phenotype = what is expressed
- gender identity present from age 2 or 3, both cisgender and transgender children identify gender reliably by age 5
congenital adrenal hyperplasia
testosterone in genetic female (xx) can cause male anatomy and brain differentiation
androgen insensitivity syndrome
lack of sensitivity to testosterone in genetic make (xy) causes no male organs; individuals often raised as female
sex linked inheritance
- males more susceptible to express recessive x-linked traits
- only one chance to get a clean copy; whatever males have will be expressed
- hemophilia, fragile x syndrome
- y-linked traits will only affect males; pass from father to son
- webbed toes
16 weeks
- can blink, grasp, move its mouth and suck its thumb
- mother may be able to feel fetus moving
18 weeks
- all organs formed, period of simple growth begins
- facial expressions
- lungs formed, but not developed enough to survive outside womb
- covered in hair and greasy substance
- fetus may be able to feel pain
20 weeks
- about 7.5 inches long, weighs about 1 pound
- has fingerprints
- facial movements- can raise eyebrows
- time of extremely rapid brain growth
- might be able to survive outside womb
22 weeks
- 8-9 inches from head to rump, weighs 1-1.5 pounds
- lungs are capable fo breathing air, may need assistance if outside womb
- can smile, grown, cry, and squint
- apoptosis begins in large scale (24 weeks)
28 weeks
between 28 weeks and term, fetus manly grows dramatically in size
- 10.5 inches from head to rump, weighs 2.5 pounds
- lungs are capable of breathing air
- hears and reacts to variety of sounds
- almost always survive outside womb
- brainwaves like newborns’
movement in fetus
- fetus move from 5-6 weeks
- 7 week old fetuses hiccup
- activity level individual differences, and there’s continuity in this after birth
- more active fetuses= more active, less inhibited children
how do fetuses practice for life outside womb?
- bringing hand to mouth
- swallowing amniotic fluid promotes development of palate and aids in maturation of digestive system
- movement of chest wall and pulling in and expelling small amounts of amniotic fluid help respiratory system become functional
- called fetal breathing- only 50% of time
- cells in visual pathway engage in spontaneous activity
fetus behavioral cycles
- young fetuses move a lot- PRETTY MUCH ALL TIME
- jerky, uncontrolled
- after 10 weeks, rest/ activity cycles every few minutes
- in second half of pregnancy, move only 10-30%- thought to be related to cortical inhibition
- most active in early morning and late evening
- by end of pregnancy, sleep about 75% of time; distinct sleep states
fetal senses
- fetus feels, tastes, smells, and hears
- feels own movements
- tastes and smells amniotic fluid (sweet= good)
- hears moms bodily sounds (loud); her voice; startles to loud sounds
- hair and neural cells tune to diff sounds from 25 weeks
- important environment isn’t too loud
- seeing minimal (eye mainly develops prenatally= they can see, but its dark!)
- cells in fetal visual pathway engage in spontaneous activity
fetal learning
- fetal habituation to speech sounds/ dis habituation to new sounds by 32 weeks (slowed heart rate= interest)
what do full term newborns prefer?
- mother’s voice and smell
- maybe helps to recognize mom- food they’ve experience prenatally
- music they’ve hear prenatally
- words they’ve heard prenatally
- words they’ve heard prenatally
- stories they’ve hear prenatally
miscarriages
- miscarriage= spontaneous abortion
- extremely common; 45%+ conceptions
- 6-15% of known pregnancies in canada
- 25-50% of women experience miscarriage
- 1% recurrent (3+ consecutive)
- most miscarried embryos have severe defects (aneuploidy- extra/ missing chromosomes)
- > 90% non-miscarried babies born fully healthy
- extremely common; 45%+ conceptions
teratogens
any environmental agent that can potentially cause harm during prenatal development
- show dose-response relation
- timing is crucial!
- cumulative impact
- individual differences matter
- fetal programming- set up for later life
- Dutch hunger winter
- sleeper effects
how to identify teratogens
- fetal alcohol syndrome:
- elfin ears
- eye fold
- large flat upper dentate
- thin lips
- small, widely spaced eyes
what can lead to teratogens?
- sleeper effects make it difficult, but:
- alcohol bad, particularly early
- smoking bad
- mercury bad
- marijuana bad
- some maternal diseases bad- very bad flu
- illegal drugs bad
maternal factors affecting fetus
- age (young and old moms (and dads) put baby at risk)
- nutrition (folic acid especially important)
- getting enough calories critical
- stress-level (high stress impacts hormone environment in womb)
- newborns of mothers depressed during pregnancy demonstrate different stress response and brain activity at birth
- IVF studies show prenatal environment means more than genetics in influencing child outcomes of maternal prenatal stress
SSRIs during pregnancy
- clear negative effects of pre and post natal depression/ anxiety on child development
- associated with deficits in attention, more impulsivity, and less cognitive control
- reduction in fetal brain connectivity
- but should you treat with meds?
- does NOT increase autism
- cardiac issues
- perhaps with-drawl symptoms at birth
3 stages of birth
dilation (long period of contractions), transitions/ birth (pushing), afterbirth
important functions of birth for baby
- squeezing of head stimulates hormones to help with breathing
- rids amniotic fluid from lungs
- washes baby in bacteria, promotes development of healthy microbiome
- c-section babies have more allergies, asthma, obesity (lack of fetal washing)
newborn states
- quiet sleep (8hrs)
- active sleep (8hrs)
- active awake (2.5hrs)
- alert awake (2.5hrs)
- crying (2 hrs)
- drowsing (1hr)
auto-stimulation theory
brain activity during REM facilitates visual development in fetuses and newborns
myoclonic twitching
jerky movements; building sensorimotor maps
colic
- inconsolable crying for more than 3 hours a day
- probably gastrointestinal
- usually goes away by 3-4 months
PURPLE program
raise awareness of early intense crying periods; effective at reducing ER visits and head trauma
- peak, unexpected, resists soothing, pain like face, long lasting, evening
risks to infant development
- prenatal: neural tube issues, miscarriage, teratogens, maternal nutrition, age, stress-levels
- postnatal: NICU
premature infants
anything under 34 weeks gestation (37 weeks after last period) considered premature
- fetuses considered viable after 24 weeks
- non-viability, incidence of lifelong problems increase with earlier birth
reasons for NICU
- prematurity related issues: immature lungs mean can’t breather on own
- low birth weight (udner 5 lbs 8 oz, 2.5 kg)
- if LBW at full term, small for gestational age
- developmental defects that are corrected post-birth; recovery from surgery in NICU
NICU effects on infants
- noise- beeping machines
- light- 24 hours/ day
- pain- pin pricks, surgical cuts
- drugs- analgesics, antibiotics, sedatives
- separation from maternal interaction
NICU effects on parents
- parents have little or no preparation for NICU experience
- depending on level of prematurity, less prepared for arrival of infants
- feelings of fear, grief, loss of control
- life or death decisions
effects of stress on development
- early pain stimuli lead to permanent changes in neuroendocrine system, in particular HPA axis (regulates stress(cortisol))
- chronically high cortisol
- associated with early onset of adult diseases: diabetes, cognitive impairment, atherosclerosis
stress effects of early repetitive pain
- injury provokes sprouting response in local sensory nerve terminal— more pain nerve
- lead to hypersensitivity to pain —> decreased pain threshold
- as adults, increased anxiety, preference for alcohol, defensive with-drawl behavior
e.g., needle pricks
stress effects of early prolonged pain
- lead to hyposensitivity to pain —> increased pain threshold
- less locomotor activity as infants
- as adults, stress/ anxiety vulnerability and cognitive deficits
e.g., result of inflammation
outcomes of NICU interventions
- immediate: reduced hospital stays, decreased likelihood for physical complications
- infancy: better developmental and interactional outcomes
- childhood: improved cognitive, motor, attentional functioning, parental perception, quality of social interactions
ELBW babies
- harder to interact with a preterm/ LBW infant, who has not finished developing
- attention: show less attention to novel stimuli, issues habituation
- self-regulation issues- difficult to settle, irritable
- sleep issues
- mixed cues in mother-infant facial exchanges
feedback loop/ cascades
- a difficult baby makes worse caregiver makes more difficult baby makes a ….
later outcomes of prematurity/ ELBW
- premature: deficits in cognition, learning disorder, attention problems, behavioral issues, motor control issues
- LBW: lower IQ, ADD, ADHD, visual perception issues, anxiety, depression, low self-esteem, complex learning disabilities
multiple risk model
long term outcomes depend on whether had one or more than one risk factor
risk factors for infant mortality
- Medical complications
- Multiple birth
- Maternal health
- Maternal age
- Teratogen exposure
- Stress
- Race
how does birth affect race?
- preterm and LBW more common amongst black and preterm amongst indigenous mothers
- black infants more likely for ELBW
- preterm birth higher in black and indigenous infants
- black infants born earlier in canada and US
- indigenous infants more likely to be preterm
parker dominguez race and birth study
- increase instance of preterm/ LBW births in black (and very likely indigenous) mothers in north America due to increased racism-related stress
- volume of black lives matter marches negatively correlated with both LBW and infant mortality, including white infants (white mortality only)
