CH 4: Prenatal Development and Birth Flashcards
Prenatal development
the changes that transform the fertilized egg into a newborn human
How long does prenatal gestation take and how much can it vary by?
38 weeks; up to 37 days/5 weeks
3 stages of prenatal development & their length
- period of the zygote - weeks 1-2
- period of the embryo - weeks 3-8
- period of the fetus - weeks 9-38
When does fertilization end?
When the zygote implants itself in the wall of the uterus
How often does cell division occur in a zygote?
every 12 hours
first stage of the period of the zygote
fertilization
implantation & how long it takes to complete
burying of the zygote into the uterine wall; about a week
how large is an implanted zygote?
diameter less than 1 mm
germ disc
small cluster of cells near the center of the zygote that will eventually turn into a baby
role of the placenta
exchange nutrients and wastes between mother and baby
what marks the end of the period of the zygote?
implantation and cell differentiation
embryo
a zygote completely embedded into the uterine wall
3 layers of the embryo
ectoderm
mesoderm
endoderm
ectoderm
outer layer of the embryo that becomes hair, outer skin & NS
mesoderm
middle layer of the embryo that will become muscles, bones and the circulatory system
endoderm
inner layer of the embryo that will become the digestive system and the lungs
3 week old embryo vs 8 week old embryo
3wk old: about 2 mm long & looks like a salamander
8wk old: about 2cm long can see eyes and limbs, heart has been beating for around a month, brain and NS are rapidly developing, too small for mother to physically feel
amniotic sac
sac where the embryo rests
2 things that link embryo to mother
umbilical cord and placenta
umbilical cord
contains the blood vessels that join the embryo to the placenta
villi
projections from the umbilical cord vessels that blood flows through; lie close to the mother’s blood vessels and allows for nutrients/waste products/oxygen to be exchanged b/w mother and embryo
2 embryo growth principles
cephalocaudal principle & proximodistal principle
cephalocaudal principle
the head develops before the rest of the body followed by arms and legs developing before hands and feet (top-down)
proximodistal principle
the center of the body grow before more distant parts (center-out)
when can most mothers feel the fetus move?
around 4 weeks/when fetus weighs 100-225 grams
how much weight does the fetus gain in the final 5 months?
3-3.6 kg
what finishing touches are put on the fetus during the fetal period?
nervous, respiratory and digestive systems
what regions of the brain grow during the fetal period?
all; particularly the cerebral cortex
when are testicles and ovaries developed?
near the end of the embryonic period
when is the sex hormone to make the fetus a male secreted/not secreted?
third month
vernix
thick substance that protects the fetus while in the amniotic sac
age of viability
age when most bodily systems function well enough to support life once the baby is born (22-28wks)
when does the developing child begin to emit behavior?
gestation
The Cat in the Hat example from prenatal development
Expectant mothers read aloud the cat in the hat to their fetuses and when the babies were born they sucked on a nipple to get their mother to read the cat in the hat but stopped when they started reading other stories
main takeaways from each period
zygote: egg is fertilized and zygote implants itself in wall of uterus
embryo: period of rapid growth and most body structures begin to form
fetus: huge increase in size and most body systems begin to work
5 steps towards a healthy baby
- visit a health-care professional for regular checkups
- professional might recommend diet supplements
- no alcohol or cigarettes and limit caffeine
- exercise throughout pregnancy
- get plenty of rest
most pregnant women need to increase their caloric intake by how much?
10-20%
what is the normal weight women weight gain at 40wks of pregnancy? and how does it al balance out?
13.9kg; 1/3 is the baby and the placenta; 1/3 is the increase in the mother’s fat; 1/3 is the increased volume of blood and breast/uterus size
when mothers do not consume enough of this, their babies are at risk for neural tube defects
folic acid
spina bifida
disorder in which the embryo’s neural tube doesn’t close properly
inadequate nourishment can impact the baby mainly how?
can impact the baby’s NS
why are there only correlational studies regarding pregnant mothers and stress?
it is unethical to subject anyone to extreme stressful situations
women who report higher stress levels during pregnancy typically what?
give birth early and have underweight babies
what are traditionally considered the prime childbearing years?
20s
what’s the suggested optimal age for having a child?
25-34
children of younger vs older mothers tended to be affected by what?
younger: infectious diseases
older: mental disorders, heart disease and circulatory disease
teenage pregnancy tends to be associated with what?
pre-term deliveries and low birth weight
main 3 general pregnancy risk factors
nutrition
stress
mother’s age
teratogen
agent that disrupts normal prenatal development
what drug was introduced to Canada and Germany in the 1950s to help pregnant women sleep better and control nausea but resulted in babies with birth defects?
thalidomide
5 most common teratogenic diseases
AIDS
cytomegalovirus
genital herpes
rubella
syphilis
consequences for developing baby from a mother with AIDS
frequent infection, neuro disorder and death
consequences for developing baby from a mother with cytomegalovirus
deafness, blindness, abnormally small head, cognitive delay
consequences for developing baby from a mother with genital herpes
encephalitis, enlarged spleen, improper blood clotting
consequences for developing baby from a mother with rubella
cognitive delay, damage to eyes, ears and heart
consequences for developing baby from a mother with syphilis
damage to CNS, teeth and bones
which diseases attack the baby through the placenta; at birth; or both
cytomegalovirus, rubella, syphilis; genital herpes; AIDS
5 common teratogenic drugs and their consequences
Alcohol: fetal alcohol spectrum disorder, cognitive deficits, heart damage and retarded growth
Caffeine: lower birth weight & decreased muscle tone
Marijuana: low birth weight & less motor control
Nicotine: retarded growth and possible cognitive impairments
Aspirin: deficits in intelligence, attention and motor skills
Doing this before pregnancy can result in lowered rates of fertility, infertility, and implantation in the fallopian tube
Smoking
Smoking during pregnancy can cause what?
Problems with the placenta, low birth weight, preterm birth, cleft palate and sudden infant death syndrome
main 2 points of FASD
children grow slower than normal and have heart problems
environmental teratogens and their effects on the baby
lead- cognitive delay
mercury- retarded growth, cognitive delay, cerebral palsy
polychlorinated biphenyls- impaired memory and verbal skills
x-rays- retarded growth, leukemia and cognitive delay
from what can PCBs contaminate animals and fish?
seeping into groundwater
pregnant women should try to do what to stay careful of the food they eat and air they breathe?
clean foods thoroughly to rid insecticides
avoid foods with chemical additives
stay away from air contaminated by household products
stay away from cats and litter boxes (toxoplasmosis)
4 main principles of teratogenic effect
- the impact of a teratogen depends upon the child’s genotype
- the timing of exposure to a teratogen plays a huge role
- teratogen harm is selective and each one affects a specific aspect of prenatal development
- damage from teratogens may not be evident at birth but can appear later in life
when can ultrasound photos determine the gender of the baby?
16-20 wks after conception
amniocentesis
a needle is inserted in the mother’s abdomen to obtain a sample of the amniotic fluid
chorionic villus sampling
a small tube is inserted into the uterus through the vagina to collect cells from the placenta
when are amniocentesis and chorionic villus sampling used?
when a genetic disorder is suspected
fetal surgery can be done how?
endoscopically or openly
how long after conception does a women typically go into labour?
38 weeks
cervix
opening at the end of the uterus that is the entryway to the birth canal
steps of stage 1 of child labour
-contractions are weak and irregular; cervix is 5cm dilated
-contractions are stronger and at regular intervals; cervix is 7-8cm dilated
-contractions are intense and can occur nonstop; cervix is 10cm dilated
what is apparently the most painful part of child labour?
the transition phase at the end of stage 1
how long does stage 1 of child labour typically last?
12-24 hrs
steps of stage 2 of child labour
-women get the urge to push the baby out with their abs
-baby is propelled down the birth canal with help from contractions and abdomen
-crowning
-baby’s birth
crowning
when the top of the baby’s head appears during labour
breech presentation
when the developing baby’s feet are facing the birth canal instead of the head
steps of stage 3 of child labour
-placenta is expelled from the uterus
-only lasts 10-15 mins
doula
a professional who provides support and education about childbirth but does not intervene medically
Caesarean section
baby is removed from the uterus by an incision in the mother’s abdomen
midwife
a non-physician who is trained to help mothers with natural vaginal delivery
why are natural methods of dealing with birthing pain emphasized over medication>
medication prevents women from using their ab muscles to push the baby through the birth canal
3 strategies offered in childbirth classes for women to counteract pain without drugs
deep breathing
visual imagery
a support coach
2 forms of lacking oxygen
anoxia: complete deprivation
hypoxia: reduced oxygen supply
when might a doctor want to do a C section?
when the fetus is in distress
one of the greatest challenges for preemie babies?
damage/underdevelopment of the cerebellum
prematurity vs small for date babies
premature: babies born earlier than full term
small for date: babies born at a lighter weight than expected for whenever they were born
small-for-date babies are often born from mothers that what?
smoked and drank during pregnancy
babies who weigh less than how much often don’t survive at birth?
1500g
small for date babies weighing more than 1500grams have better chances of survival but still may experience what?
lower developmental level than others
what turns out to be one huge factor for at-risk newborns as they develop?
environmental factors
“development proceeds best when women receive ________ and _________”
good prenatal care; children live in a supportive environment
Apgar score
measured used to evaluate a newborn’s vital signs
5 vital signs of a newborn
breathing
heartbeat
muscle tone
presence of reflexes
skin tone
5 measures on the Apgar scale
activity
pulse
grimace
appearance
respiration
an Apgar score of what indicates a baby in good condition?
7 or higher
a score of what on the Apgar test indicates a life threatening situation for the baby?
3 or lower
newborns spend most of their alternating between what 4 states?
alert inactivity (calm baby)
waking activity (uncoordinated and unfocused)
sleeping
crying
3 types of baby cries
basic
mad
pain
how often do newborns sleep daily?
16-18hrs
sleep-wake cycle of newborns
sleep for 3 hours;awake for 1 hour
roughly half of newborns sleep is what kind?
REM sleep
sudden infant death syndrome
a healthy baby dies suddenly for no apparent reason
when is SIDS more likely?
preemies/small-for-date babies
parents smoke cigs
baby sleeps face down
during the winter
postpartum depression
low self worth, disturbed sleep and poor appetite that 10-15% of new mothers feel for months after birth
children of mothers who suffer from PPD for months on end are at higher risk for what?
having depression themselves and other behavior problems
how many centres in the world do fetal surgery?
2
