HHD Chp 4

Germinal Period

weeks 0-2 of pregnancy (from conception); rapid cell division and beginning of cell differentiation

embryonic period

approximately weeks 3-8 of pregnancy (from conception); basic forms of all body structures, including organs, develop

fetal period

week 9-birth of pregnancy (from conception), fetus gains about 7 pounds (more than 3000 g) and organs become more mature, gradually able to function on their own 

gestational age 

age of pregnancy as measure from conception

embryo

organism becomes an embryo 2 weeks after conception (pregnancy is detectable), some people measure pregnancy as starting from here

LMP

last menstrual periods, roughly 14 days before conception; some obstetricians and publications count pregnancy from here (this is where 40 weeks would be considered full term)

length of pregnancy

266 days (38 weeks)

trimesters

an alternate way to divide length of pregnancy; split into 1st (months 1-3), 2nd (4-6), 3rd (7-9). 

due date

calculated based on LMP (40 weeks out), only 5 % born on due date

full term

babies born between 2 weeks before and one week after due date

one week after conception 

developing mass forms a steel and a nucleus that will respectively become the placenta and embryo

implantation

happens at 10 days, shell burrows into the lining of the uterus; high failure rate (zygote isn’t developing properly, lining not receptive, or many other reasons)

vulnerability stats

65% of zygotes don’t survive germinal period, 20 % don’t survive embryonic (spontaneous abortion; early miscarriage- usually chromosomal malformation), 5 % aborted spontaneously before viability at 22 weeks or stillborn (dead after 22 weeks- more common in low income nations)

What percentage of zygotes grow and survive to become newborns?

27%

embryo

name for a developing human organism from about the third week through eight week of conception

primitive streak

a thin line that appears down the middle of the embryo; at 22 days after conception it will form the neural tube

central nervous system

the spine and the brain; forms from the neural tube

when do fingers and toes separate

respectively 52 and 54 days after conception

what all forms in embryonic period?

head with eyes, ears, nose, and mouth

blood vessel that will become the heart

limbs begin to bud and form

elbows and knees (by week 8)

cephalocaudal + proximodistal 

the ways in which development occurs; head to tail and near to far; so head forms first and extremities last; continues until puberty when it reverses 

indifferent gonad

the embryo has both male (wolffian ducts) and female (Müllerian ducts) potential; one will shrink due to genetic and hormonal influences at the end of embryonic period; genitals grow from that gonad

fetus

name for a developing human from start of the ninth week after conception until birth

3-3-3

by 3 months fetus’ are about 3 inches long and weigh 3 ounces

hormones and fetal brain

a controversial topic; differences appear when average male is compared to average female but overlap is common; most brains are a male-female mosaic

middle 3 months (2nd trimester)

4 month old fetus has large body movements (whole body extension and flexion and stretching); rate of miscarriage plummets from 10% (week 5-12) to 2 % (week 12-20); HR speeds up; digestion and elimination; fingernails, toenails, and buds for teeth; hair and eyelashes; 

awakening of central nervous system! -why at 22 weeks become viable because advanced tech cannot maintain life w/o brain response 

final 3 months (3rd trimester)

neurological, respiratory, and cardiovascular systems all develop! Brain most important- human brain growth so extensive that the cortex becomes wrinkled- estimated 86 billion brain cells (neurons) at birth; neurons get pruned; and membranes and bones covering the brain thicken

on average weight gain of 4.5lbs

apoptosis

cell death! As many as half of all neurons die - abnormal or immature ones ; genetically directed as fetal brains adjust to the environment

fontanels

areas on top of the newborn head where the bones of the skull have not yet fused - makes head narrower for passing through birth canal; close following birth 

neural progenitor cells

multiple and duplicate many times to become neurons

fetal brain development

a frontier of science but exceptionally difficult partially because brain development switches from the first six moths to the final three

to start basic structures (limbic system, prefrontal cortex, etc)-malformation in any alters mind and behavior lifelong

4th month: explosion of new cells in the hippocampus (memory formation) but then slowdown in growth

final three months; fewer new brain neurons formed so existing ones respond to stress, sleep, diet, exercise, and so on (environment becomes very essential) prenatal experiences stored in pre-birth memory neurons

hormone that signals the start of labor

oxytocin

timing of labor

typically 12 hours for first labor and 7 hours for subsequent ones

birthing position and location

culturally and personally dependent!! although in places where people birth in hospitals, mothers tend to be supine

anoxia

a lack of oxygen; contractions during labor result in momentary anoxia which slows fetal HR-closely monitored because anoxia can increase risk of cerebral palsy; twins and breech births at highest risk

cerebral palsy

condition where the brain has noticeable difficulties with movement; used to be believe it was caused solely by birth procedures; actually begins with genetic sensitivity

US home births

less than 2% of babies are born at home; and of that half is due to unexpected quick progression of labor

high income nation with the most home births

netherlands; increasing since COVID; national healthcare provides money, trained midwives, and special ambulances called flying storks (trip to nearby hospital pending complications)

doula 

a person who helps with the birth process. Traditionally, in Latin America, a doula was the only professional who attended childbirth. Now doulas are likely to arrive at birthing parents home during early labor and later work alongside hospital staff; particularly helpful for parents who feel intimidated by hospitals (immigrants, low income, etc)

Apgar Scale

Developed by Virgina Apgar because delivery rooms neglect newborn health. A quick assessment of a newborn’s health, from 0-10. Below 5 is an emergency- a neonatal pediatrician is summoned immediately. Most babies are 7,8,9 but 10s are rare. Measures appearance, pulse, grimace, activity, respiration (color, heart rate, cry, muscle tone, and breathing); goal is 7 at birth and 10 at 10 minutes after

cesarean section

fetus removed via an incision in the abdomen; medically indicated for about 10-15 % of births; many indicators but no one indicator will absolutley require c-section; decision affected by personal experience and political values; worldwide about 21% are cesareans 

disadvantages of C-section

less breastfed c-section babies and more experience medical complications and have higher rates of asthma, diabetes, and obesity (partially because the miss robust microbiome enhancers of birth canal)

vaginal birth after cesarean (VBAC)

a movement in US in opposition to all subsequent births being a cesarean once you have had one; US rate of VBAC is 14%

Pitocin 

precipitates labor and speeds up contractions; can increase pain but it removes risk of eclampsia (maternal blood pressure spikes so high it could cause death) 

epidural

injection in the spine to stop sensation in the lower body; reduce pain but increase rate of c-sections

teratogen

anything- drug, virus, pollutant, malnutrition, stress,etc- that increases the risk of prenatal anomalies and birth complications; physical ones recognized about 6 decades from when textbook published; took a while to realize there were behavioral ones

behavioral teratogen 

affect what a person does, not how they appear 

ZIKA virus

recognized as a teratogen in 2015; caused by mosquito bite; epidemic led to microcephaly but before that had been causing undetected issues for years

timing is crucial

germinal and embryonic period crucial for body formation

brain development and weight crucial later; first 8 weeks called the critical period but all are important

threshold effect

case for many teratogens; they have no impact until they reach a certain level and then cross the threshold to damage

fetal alcohol syndrome 

a cluster of birth defects, including atypical facial characteristics, slow physical development, and reduced intellectual ability, that may occur in the fetus of someone who drinks alcohol while pregnant. - specifically early in the pregnancy 

fetal alcohol effects

when drinking later in pregnancy causes behavioral affects

factors of cascade of prenatal harm

timing, dose/frequency, genetics, drugs, pesticides, low birth weight

neural tube malformations

caused by lack of folic acid; spina bifida (spine not enclosed at bottom) and anencephaly (brain missing partially)

data desert 

estimated 90% of drugs have insufficient data regarding the effect on the fetus; therefore analysis of risk and benefit is needed (best avoid alcohol and cigarettes and non essential drugs while continuing essential drugs)

covid 19 and pregnancy

complications were twice as high for unvaccinated mothers compared to vaccinated; COVID-19 and pregnancy both strain the lines and the heart, reducing oxygen to fetal brain

pesticides

pregnant people who breath or ingest pesticides are at an increased risk of miscarriage and having a baby born with brain damage c

chlorpyrifos

cheap and effective pest control; bioaccumulates and stays in bodies; it affects placenta and brain of the human fetus; lower IQ and behavioral difficulties

low birth weight

babies born under 5.5lbs or 2.5g

very low birthweight

under 1.5g or 3lbs 5oz e

extremely low birthweight

under 1g or 2lbs 3oz

low birth weight percentages

more than 8% in US are LBW and less than 1% are ELBW

preterm 

2 or more weeks before due date; 10% of all US births

small for gestational age/ small-for-dates

a newborn whose birthweight is significantly lower than expected, given the time since conception. 5lbs baby is considered SGA if born on due date but not if born 2 months early

causes of SGA

1.malnutrition

2.drug use

3.multiple births

consequences of LBW

typically:

developmental milestones are all delayed

cognitive, hearing, visual impairments common

cognition in kindergarten impaired

neurological problems- lead to social issues

higher risk of diabetes, obesity, heart disease, and depression

couvade syndrome

symptoms of pregnancy and birth experienced by partners of pregnant people; “somatic pregnancy symptoms”- nausea, leg cramps, appetite and mood changes, and weight gain

immigrant paradox

the surprising, paradoxical fact that low-SES immigrant birthing parents tend to have fewer birth complications than native born peers with higher incomes; hypothesis: immigrants are particularly likely to support pregnant relatives

LBW paradox

LBW is decreasing in most nations but increasing in some- the US among them

hypothesis: not multiple births, not lack of prenatal care, perhaps food scarcity leading to poor maternal nutrition (supported by a couple studies), perhaps drugs use (e-cigs are more common and correlated with LBW)

reflex 

an involuntary response to a particular stimulus 

3 reflexes that sustain life

maintain oxygen (hiccups, sneezes, trashing to escape covers), maintain constant body temp (shivering, cry, tuck legs or push away blankets), manage feeding (sucking, rooting (turn mouth towards anything that brushes cheeks), swallowing, crying for empty stomach)

postpartum depression

a new parent’s feelings of inadequacy and sadness in the days and weeks after giving birth; partially causes by hormone spike and fall from birth; nations rate ranges from 5-27%; euphoria right after birth than anxiety and severe depression may set in and last for 2-3 moths 

causes of PPD 

can predate pregnancy, occur during pregnancy, or being associated with the birth itself 

parent-infant bond

strong, loving connection that forms as a parent holds, examines, and feeds their newborn; found that first few hours are not necessarily crucial for primates and humans; bonds can begin before birth or may not be established until weeks later

kangaroo care

a form of newborn care in which parents rest their babies on their naked chests, like a kangaroo mother carries newborn in pouch; demonstrates benefits of early contact; helps newborns sleep more deeply, gains more weight, and spend more time alert, and are overall healthier; may even undercut hormones that promote PPD