Prenatal development and newborns

timeline of prenatal development

conception (beginning of pregnancy)

period of the zygote (weeks 1-2)

period of the embryo (weeks 3-8)

period of the fetus (weeks 9-birth)

period of the zygote

period of rapid cell division

• blastocyst formed within 4 days of conception

• cell differentiation has already begun at this point

begins with egg being fertilized in fallopian tube, ends with zygote implanted in wall of uterus

what must occur during the window of implantation?

once zygote in uterus, implants into uterine wall and connects with mother’s blood supply

period of the embryo

begins with implantation, after which required support structures develop, including amnion, chorion, placenta, umbilical cord

amnion

amniotic sac full of amniotic fluid, important for cushioning against impact, regulates temperature, provides weightless environment for development

chorion

membrane that surrounds amnion, becomes lining for placenta later

placenta

very important for fetal development, fed by blood vessels from both mother and embryo, which allows transfer from mother to fetus

umbilical cord

transports oxygen out of embryo to mother

embryo starts as a single layer but folds itself into

the ectoderm, mesoderm, and endoderm very quickly (three layers)

ectoderm

top layer, becomes nervous system, teeth, nails, inner ear, outer skin, etc

mesoderm

middle layer, becomes muscle, bones, circulatory system, inner skin layer, etc

ectoderm

innermost layer, becomes digestive system, lungs, glands, urinary tract, etc

portion of it forms the neural tube, happens a few days after the other layers form

neural tube

U shaped groove forms down ectoderm, one end develops into brain and rest into spinal cord

in second month during embryo period, development and growth happens rapidly, with

eyes and ears forming, rudimentary skeleton, limbs develop, brain develops rapidly, indifferent gonad appears (eventually becomes ovaries or testis depending on sex chromosomes)

period of the fetus

longest period, from week 9 to birth, size grows rapidly throughout

fetus period- month 3

able to kick, twist, but not felt by mother

can swallow, digest, urinate

testosterone secreted by testes of males, ultrasound can detect sex

fetus period- months 4-6

more refined motor actions (e.g. thumb sucking)

kicking may be felt by mother

heartbeat can be heard with stethoscope

eyebrows, eyelashes, scalp hair appear

covered in vernix and lanugo

vernix

white, cheesy covering to prevent chapped skin

lanugo

fine layer of body hair, regulates temperature

fetus period- months 7-9

finishing phase, organ systems mature, weight gain

moves to head-down position in last month

age of viability

at 22-28 weeks, survival outside uterus possible

very hard on fetus, but can happen

fetus experience- movement

spontaneous ones start about 5-6 weeks after conception, more distinct ones begin around 7 weeks—i.e. hiccups, swallowing, related tongue movements

when does fetal breathing begin?

around 10 weeks, increases over time

fetus experience- touch

various forms, i.e. tactile stimulation, have been observed

grasp umbilical cord, rub face, suck thumb

by end of gestation, fetus responds to mother’s movements, indicating vestibular senses

fetus experience- sight

minimal experience overall, but prefer a top heavy pattern because it resembles face shapes

by 3rd trimester, fetuses can process visual information and have preferences

fetus experience- taste and smell

amniotic fluid contains a lot of flavours and fetuses seem to prefer certain ones, such as sweetness

amniotic fluid also leads to olfactory experience as it contacts fetus’ odour receptors

has an impact on newborn preferences for certain smells and tastes

fetus experience- hearing

can hear many sounds throughout prenatal development—parent’s heartbeat, blood flow, breathing, digestive sounds, voices

can see fetal responses to sounds, with changes in heart rate or movement

hearing a parent’s voice can cause fetus to

change heart rate

hearing external noises can cause fetus to

engage in movement

fetal auditory experiences are important for

brain development, with longer-term impacts evident

learning- habituation phase

repeatedly present stimulus and measure responses

newborns get bored when shown the same thing over and over again, will respond less

learning- recovery or dishabituation phase

present new or changed stimulus, see if recover response

newborns can detect this change and reengage with stimulus

DeCasper and Fifer 1980 study

preferential listening paradigm combined with operant conditioning

sucking response measured

operant conditioning procedure with 3-day old infants, training sucking response to mother’s voice (specifically measured interburst interval, shorter indicates more sucking)

found that infants could differentiate mom’s voice from other female voices and could be trained to suck more to hear mom’s voice

teratogens

any potentially harmful agent that can impact prenatal development, such as some prescription medications, alcohol, nicotine, other substances, pollutants

co-occurrence is common—hard to differentiate effects, leads to cumulative effects

affect fetus in different ways, to different extends, depending on dose timing, genetic risks, etc

maternal factors

age, prenatal nutrition, disease/illness, mental health/stress, SES

paternal factors

age, physical health prior to conception

which period is most sensitive?

embryo period, because this is when a lot of development is happening

ultrasound

sound waves used to generate an image of the fetus

determine due date and position of fetus in uterus, check for physical deformities, multiple births, and sex

amniocentesis

sample of fetal cells are obtained from amniotic fluid

used to screen for genetic disorders

chorionic villus sampling (CVS)

sample of tissue obtained from the chorion (part of placenta)

used to screen for genetic disorders

first stage of labour

before labour begins, contractions are 10-15 mins apart

transition occurs just before the baby’s head enters birth canal

ends with cervix fully dilated to 10 cm

second stage of labour

begins when baby’s head emerges from birthing canal/before crowning, ends when head out

third stage of labour

placenta comes loose and about to be born, delivery occurs

labour- fetus experience

crowning, squeezing- can affect head shape

stressful process

hormone production to help with process

labour- mother experience

pain

hormonal reactions and responses

mixed emotions and stress common

engrossment or fascination with newborn

skin to skin contact

risk of postpartum depression

labour- father experience

mixed emotions and stress common

engrossment or fascination with newborn

skin to skin contact

a lot of diversity in birthing process, but typically has 3 key goals

survival and health of mother and baby

comfort of mother and baby

social integration of new person

labour decisions and potential issues

who is involved, location, use of medication, birthing environment, mode of delivery, process immediately after delivery

apgar test

newborn assessment, assesses activity, pulse, grimace (response to irritating stimulus), appearance (skin colour), respiration, scored from 0-2

7 or higher means generally healthy, 4 or lower requires immediate medical attention

many potential complications can occur, negatively impacting development to varying degrees, including

anoxia, birth defects (known or unknown), low birth weight, infant mortality, impacts of systematic racism

newborn survival reflexes

breathing, eye-blink, pupillary, rooting, sucking, swallowing

newborn primitive reflexes

babinski, palmar, moro, swimming, stepping

breathing reflex

repetitive inhalation and expiration

permanent

provides oxygen and expels carbon dioxide

eye-blink reflex

closing or blinking the eyes

permanent

protects eyes from bright light or foreign objects

pupillary reflex

constriction of pupils to bright light; dilation to dark or dimly lit surroundings

permanent

protects against bright light, adapts the visual system to low illumination

rooting reflex

turning head in direction of tactile stimulus to cheek

disappears over the first few weeks of life and is replaced by voluntary head turning

orients baby to breast or bottle

sucking reflex

sucking on objects placed (or taken) into the mouth

permanent

allows baby to take in nutrients

swallowing reflex

swallowing

permanent

allows baby to take in nutrients

babinski reflex

fanning then curling the toes when bottom of foot is stroked

usually disappears within first 8 months to 1 year of life

presence at birth and disappearance in first year indicate normal neurological development

palmar reflex

curling fingers around objects (such as finger) that touch baby’s palm

disappears in first 3-4 months and is then replaced by a voluntary grasp

presence at birth and disappearance in first year indicate normal neurological development

moro reflex

loud noise or sudden change in position of baby’s head causes baby to throw arms outward, arch back, bring arms toward each other as if to hold onto something

arm movements and arching of back disappear over first 4-6 months, but child continues to react to unexpected noises or loss of bodily support by showing a startle reflex (which does not disappear)

presence at birth and disappearance in first year indicate normal neurological development

swimming reflex

infant immersed in water will display active movements of arms and legs and involuntarily hold their breath (buoyancy); will keep them afloat for some time, allowing easy rescue

disappears in first 4-6 months

presence at birth and disappearance in first year indicate normal neurological development

stepping reflex

infants help upright so that their feet touch a flat surface will step as if to walk

disappears in the first 8 weeks unless infant has regular opportunities to practice this response

presence at birth and disappearance in first year indicate normal neurological development

infant states

quiet sleep, active sleep, drowsing, alert awake, active awake, crying

infant states- quiet sleep, active sleep, drowsing

newborns sleep twice as much as adults, initially need 16 hours of sleep a day

total time declines regularly throughout childhood and more slowly throughout life

infant states- alert awake, active awake, crying

cry for lot of reasons, it is adaptive

peaks around 6-8 weeks, decreases around 3-4 months

lot of early focus on soothing newborn, with cultural variations in how to do so

colic

excessive, inconsolable crying by a young infant for no apparent reason

responding to newborn distress

conflicting results

quick response results in less crying several months later

ignoring it during first 9 weeks reduces crying during next 9 weeks