Chapter 4 - Prenatal Development and Birth Flashcards
Ovulation occurs after?
Estrogen release
When does the premenstrual period occur?
When estrogen and progesterone both drop dramatically
When is the best time to have sex for conception? Why is this?
On the days leading up to ovulation. Because these days have higher fertility levels.
What does BBT stand for?
basal body temperature
When does basal body temperature drop? When does it begin to rise again?
During the fertile window, and it drops even more on the day of ovulation. It begins to rise after ovulation.
How can someone test to see if ovulation is, in fact, occurring?
They can map out several cycles. If there isn’t a sustained rise in basal body temperature (10-12 days), ovulation may not be occurring.
Conception and Implantation process
Day 0 - fertilization, we now have a zygote
Day 1 - first cleavage
Day 2 - 2-cell stage then 4-cell stage
Days 3-4 - 8 cell compacted morula
Day 5 - Early blastocyst (inner cell mass will become embryo, outer cell mass will become placenta)
Day 6-7 - Late stage blastocyst (hatching), around the cell forms a thing called zona pellucida
Day 8-9 - implantation of the blastocyst
Cleavage
Cell division during early early development
Morula
8-cell mass in spherical form, 3-4 days post fertilization
Blastocyst
Cell mass with a cavity 4-5 days post fertilization. Contains inner mass (will become embryo) and outer mass (will become placenta)
Implantation
Beginning about 1 week post conception. The burrowing of the organism into the uterine lining where it is nourished
Germinal period
the first 2 weeks of development after conception
After a week of conception, the cell mass, now called a blastocyst, forms two distinct parts - a shell that will become the placenta and a nucleus that will become the embryo
First task: Implantation which is the process, beginning about 10 days after conception, in which the developing organism burrows into the placenta that lines the uterus, where it can be nourished and protected as it continues to develop
Embryonic Period
the 3rd to 8th week after conception
Formless mass of cells becomes a distinct being
This is when it becomes an embryo which is the name for a developing human organism from about the third through the either week of conception
Fetal Period
from the end of the embryonic period until birth (the 9th week - birth)
When is pregnancy established?
Once the embryo (conceptus) has implanted into the uterus
What does hCG stand for?
Human chorionic gonadotropin
What does human chorionic gonadotropin block?
Regression of the corpus luteum, therefore mensturation does not occur
What does a pregnancy test test for? Why?
Human chorionic gonadotropin, because only a developing embryo can produce this
What % of pregnancy ends in live birth?
80%
What % chance that the baby will survive infancy?
> 90%
What % of human embryos are genetically abnormal and have little to no chance of giving rise to a viable (able to live after birth) child?
> 50%
What do half of miscarriages have? What percentage of live birth has answer?
Chromosomal abnormalities. 0.5%
Ectopic Pregnancy? % that this occurs?
Location of implantation other than the uterus, 1%
What is the most common site for ectopic pregnancies?
Oviducts
What do ectopic pregnancies lead to?
Miscarriage, can rupture and be life threatening
What is Rhesus (Rh) incompatibility?
When the mother is not compatible with rhesus
What happens if the mother is Rhesus incompatible?
She develops antibodies against Rh and antibodies cross the placenta and attack the fetus
Why does a mother’s Rhesus incompatibility affect only her second, third and so on pregnancy?
Because in order for it to affect her, her baby’s (who posseses Rh) blood would have to mix with her. This happens when she gives birth, and she gets the shot right after, so the antibodies don’t have time to develop fast enough to attack the placenta.
What shot do Rhesus incompatible mothers receive after their first birth? What does this shot do?
Rh-specific immunoglobin, it binds to the Rh and ‘hides’ it from the maternal immune system
Why would a Rhesus incompatible mother have to receive her shot before she gives birth if she gets into an accident?
Because the baby’s and mother’s blood might have a chance to mix.
Where is Rhesus (Rh) located?
The surface of red blood cells
Primiparous
A pregnant women who has not given birth or only given birth once
Multiparous
A pregnant woman who has given birth more than once
Gestational Age
Fetal age given from the time of ovulation
Menstrual Age
Fetal age given from the onset of the last menstrual period, which is 14 days before conception
Which age is inaccurate? Menstrual or gestational? Why?
Menstrual, because the doctor asks you when your last period was, and tells you how long you’ve been pregnant, when you’re actually 2 less weeks pregnant than your doctor claims.
What % of babies are born on their due date?
5%
Pregnancy cannot be confirmed until ____
Implantation
How many more calories should a pregnant woman consume than usual?
300 calories
Where do the extra 300 calories consumed by a pregnant mother go to?
Most goes towards extra energy for fetal development and the rest goes to fat accumulation
Why does a fetus need a fresh supply of calories daily?
Because it cannot survive off maternal fat deposit
Around how much weight does a pregnant woman gain?
25-35 pounds
What does a mother ingesting folic acid do to her child?
The child might have Spina Bifida (neural tube defect where bones of the spine don’t form properly around part of the baby’s spinal cord)
What does a mother ingesting vitamin A and D do to her child?
The child might be retarded
During embryo development (3-8 weeks) how many layers does the developing organism begin differentiating into?
3
Neural tube
A fold of outer embryonic cells that appears about the 3 weeks after conception and later develops into the central nervous system
What week does the head start to take shape?
4th
What does a blood vessel become in the 4th week?
The heart
Neural plate
-A primitive neural tissue- occupies that outermost layer of the embryonic cell
Neural groove
The neural plate folds to form the neural groove
Anterior neural fold
When this closes, it forms the brain
Process of gross development?
A primitive neural tissue (neural plate) occupies the outermost layer of the embryonic cell. The neural plate folds to form the neural groove. The neural groove curls to form the neural tube. The anterior neural fold closes to form the brain.
Sex organs are identical, and only begin to take shape in the __rd month
3rd
Through the 7th week, males and females are ____
identical
By __th week external genitalia are formed
12th
Newly formed sex organs will begin to send ____ to the developing brain, directing small variations.
hormones
By end of 3rd month, fetus has all its bodily parts. How much does it weigh, and how long is it? At this stage, the placenta is fully ____
3 ounces and 3 inches
formed
Meconium?
Fills the digestive system of fetuses, kind of like sticky tar
What happens in the middle 3 months?
Digestive system develops
finger and toe nails, teeth buds, hair and eyelashes
Extreme brain growth – and begins to react to stimuli
What happens to the brain at 28 weeks?
brain wave patterns shift from a flat pattern to occasional bursts of activity (sleep-wake cycles)
At 28 weeks and 3 pounds, what are the chances of survival?
95%
Brain weight (g) 20 weeks gestation Birth 18 months 3 years Adult
100 400 800 1100 1300-1400
Genes and ____ interact throughout brain development
environment
Genes form neurons and make ____ among major brain regions
connections
Anatomy is programmed by our genes but there is some fine tuning done by _____ and ____. Enhancing connections while ____ others.
Experience, environment
Eliminating
Brain development is dependent on?
Activity and experience
Maternal Serum Screening
Tests – include ultrasound and blood test to screen for Down Syndrome and Spina Bifida
Nuchal Fold Test
ultrasound measurement of the skin fold at neck of fetus, prenatal diagnosis of Down Syndrome / congenital abnormalities
Amniocentesis procedure?
- A fine needle is inserted into the amniotic sac
- Under ultrasound guidance
- A sample of amniotic fluid, containing free-floating cells derived from the fetus, is removed
Amniocentesis
Medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections
Chorionic Villus Sampling
Alternative to amniocentesis
Can be done earlier
Can be examined directly – no tissue culture
Higher risk of miscarriage
Chorionic Villus Sampling procedure?
- A catheter is passed through the cervix into the placenta
2. A small fragment of placental tissue derived from the fetus is removed
What happens in the final 3 months of pregnancy, development wise
Maturation of the respiratory and cardiovascular systems
Lungs begin to expand and contract – exercising muscles involved in breathing (using amniotic fluid instead of air.
Fetus gains about 4.5 pounds or more in last 10 weeks – to about 7.5 pounds
Most of the weight gain is fat to provide calories that will be burned while the mother’s breast milk is established
Teratogens
Any agent or condition that can disturb the development of an embryo or fetus. Teratogens may cause a birth defect in the child. Or a teratogen may halt a pregnancy outright.
What does the impact of teratogens depend on?
When the fetus was exposed
Sensitive Period
periods during development when the brain is more responsive to stimulation from the environment – gradual
Critical Period
is a limited time in which an event can occur, usually to result in some kind of transformation – time frame
could be a small amount but have an affect because it happens during critical period
Periods of Fetal Development 1 Ears 2 Teeth 3 Palate 4 Upper Limbs 5 Lower Limbs 6 External Genitalia 7 Heart 8 Eyes 9 Central Nervous System
1 - 4 1/2 to 20 weeks 2 - 6 3/4 weeks to full term 3 - 6 3/4 to 16 weeks 4 - 4 1/2 to 9 weeks 5 - 4 1/2 to 9 weeks 6 - 7 weeks to full term 7 - 3 1/2 to 9 weeks 8 - 4 1/2 weeks to full term 9 - 3 weeks to full term
What is a possible consequence of this on a fetus: Alcohol
Fetal Alcohol Syndrome or Effects
What is a possible consequence of this on a fetus: Tobacco
miscarriage, prematurity, low birth weight (LBW), sudden infant death syndrome (SIDS), malformations
What is a possible consequence of this on a fetus: Accutane
heart & brain malformation, Retardation
What is a possible consequence of this on a fetus: Androgens / Estrogens
external genitalia / reprod. tract
What is a possible consequence of this on a fetus: Aspirin
hemorrhage in fetus / mother / new born
What is a possible consequence of this on a fetus: Heroin
miscarriage, LBW, addiction, slower fetal growth
What is a possible consequence of this on a fetus: Cocaine
neonatal intoxication, addiction, growth retardation, placental problems
What is a possible consequence of this on a fetus: X-rays
increased risk of childhood cancer
What is a possible consequence of this on a fetus: High Body Temperature
variety of birth defects
Why do you need to perform a cost benefit analysis when it has to do with expecting mothers and aspirin?
Some illnesses need aspirin. So you have to see what time in development it is as well as how much the mother needs it.
Describe the HPA axis.
fetal hypothalamic pituitary adrenal axis:
- Hypothalamus
- Pituitary Gland
- Adrenocorticotropic hormone is released into adrenal glands, from which cortisol and epinephrine and norepinephrine are released
What do stress hormones do to a developing brain?
They impede them
What helps a child’s fetal hypothalamic pituitary adrenal axis
Parent-child interactions
During pregnancy, the fetal hypothalamic pituitary adrenal axis axis is programmed to respond ____ to stress, which has the potential for protecting the fetus from increased levels of maternal stress hormones (glucocorticoids).
Less
What do increased levels of circulating glucocorticoids do to a developing brain?
They decrease neurogenesis (formation of new neurons), synapse formation, dendritic branching and influence white mater development.
Why is the placenta referred to as a “selective barrier”?
Because it protects the fetus from the mothers immune response, but lets nutrients in
What enzyme does the placenta produce during pregnancy? Why?
11β-HSD2 enzyme
serves as a glucocorticoid barrier prevents maternal cortisol from crossing the placenta into the fetal circulation
What happens to the 11β-HSD2 enzyme if the mothers stress is long lasting?
constant prolonged stress = the levels of enzyme go down because of the glucocorticoid
What do glucocorticoids do to a fetus?
Affects growth of fetus
Preclempsia
Pre-term delivery
Factor Reduced uterine and umbilical blood flow
Postpartum
weeks after birth
lochia
bloody discharge that continues for several weeks after birth
Postpartum Depression
depression in the mother during postpartum
i.e. Sadness, crying, suicidal feelings
Depressive Psychosis
depression accompanied by distorted thought, can lead to
infanticide or suicide
endogenous and environmental factors
Uterus gradually shrinks and Estrogen & Progesterone eventually return to normal
yep
How does the fetus prepare for child birth?
Corticosteroid release from adrenal glands – response to fetal hypothalamus and pituitary glands
What does Corticosteroid release do during childbirth?
- Reduces tension of fluids in the lungs, for breathing
- Instructs the fetal liver to manufacture glycogen for brains glucose needs before, during and after labour
- Triggers the blood production site to change from liver to bone marrow
- Triggers the type of hemoglobin in the red blood cells to operate from low to high oxygen levels
Lightening
the sinking of a fetuss head into a lower position in the pelvis in
preparation for birth (also called engagement)
Contraction
in childbirth, a periodic coordinated tightening of the uterine musculature, felt as a cramp
What happens to the cervix in order to allow the passing of the fetal head?
Cervix softens (softening) and thins out (effacement) and opens (dilation)
Why is the amniotic fluid sometimes discolored?
the fetus has passed meconium: dark green material that is the feces of a newborn infant
Discharge of mucous plug that seals off the cervix during pregnancy
yep
What happens if the amniotic sac ruptures early or late in labor?
baby may be born in the caulunruptured sac
Effacement vs Dilation of cervix
Effacement: the cervix thins out
Dilation: it opens
First stage of labor is divided into two phases, what are they and what are their attributes?
1) Early Phase: 0-4 cm dilation – contractions 15-20 mins apart – lasts 6-12 hours
2) Active Phase: 4-10 cm dilation – contractions 2-3 mins apart - lasts 4-8 hours. Last part of this phase is called the transition phase: very intense and frequent contractions
(what we actually refer to as the labor portion)
What are the 3 stages of labor?
- Uterine Contractions
- Delivery
- Delivery of Placenta
Can the delivery of a fetus be accomplished by contractions alone?
Yes
Episiotomy
a surgical incision of the perineum (the area between the anus and the vulva) and the posterior vaginal wall generally done by a midwife or obstetrician during second stage of labor to quickly enlarge the opening for the baby to pass through.
How long on average does it take after the fetus is delivered for the placenta to be delivered?
Up to an hour, average time 30 minutes
4 causes of Postpartum Hemorrhage
1) Tone: tone of the uterus. If the uterus does not contract down following the delivery of the placenta, hemorrhaging will occur. Blood vessels to the placenta go through the uterine muscle fibres – when uterus contracts, the vessels are pinched off (you need the contraction to pinch off your blood vessels)
2) Tissue: Any remaining tissue of placenta, uterus cannot contract properly. Ripped cord
3) Trauma: Vaginal tear, cervical tear
4) Thrombophilia: Blood clot disorders i.e. hemophilia
Shoulder Dystocia
During labor, the shoulder is caught in the pelvic bone – result of the pulling by the person delivering the baby
Brachial Plexus Injury
cervical nerve roots coming out of C4-C7 get damaged • Results in Erbs Palsy of the right arm (becomes limp)
Failure to Progress? What are the causes?
No progress in 2 hours during pushing in primips
No progress in 3 hours with epidural in primips
No progress in 1 hour with multips
1) Passenger: fetal position
2) Passage: small/narrow pelvis
3) Power: maternal exhaustion
Mal Presentation
Any presentation other than a vertex presentation (with the top of the head first).
Breech
Fetus is presenting with head up (feet first)
Face Presentation
Fetus is coming out with neck distended, with the chin coming out first
Brow Presentation
Fetus is coming out with neck straight (good posture), forehead/brow coming out first
Occipito – posterior position
The occipat (back of head) is towards the sacrum (triangle on bottom of spine), either to the left or right side
Types of breech
Frank Breech (65%) - The baby's hip joints are flexed and knee joints are extended Complete Breech (10%) - The baby's hip and knee joints are flexed Footling Breech (25%) - The baby's hip and knee joints are extended on one or both sides Kneeling Breech (25%) - The baby's hip joints are extended and knee joints are flexed on one or both sides
Nuchal Cord
A normal delivery, the OB or midwife will run their fingers
around the fetal neck to check for nuchal cord
If the cord is loose around the neck, they will loop it over
If the cord is tight around the neck, they will clamp off the cord and delivery the baby immediately
Caesarean section (c-section)
A means of childbirth in which the fetus is taken from the mother surgically through incision
Anoxia? Prolonged anoxia leads to?
A lack of oxygen that, if prolonged, can cause brain damage or death
Cerebral Palsy
Cerebral Palsy
A disorder that results form damage to the brain’s motor centres, usually as a result of events during or before birth. Have problem with muscle control. Genetic vulnerability
Birth complications and maternal infections have been shown to be a risk factors for the development of certain illnesses such as:
schizophrenia, ADHD, and substance abuse
Main hormone that triggers lactation is called:
prolactin, released from pituitary glands
Continued secretion of prolactin depends on a reflex triggered by?
baby’s suckling
Prolactin is responsible for? Whilst Oxytocin is responsible for?
Producing the milk, pushing the milk out
How does content of breast milk change?
A lot less fatty later on
Colostrum
produced during first few days, low in fat rich in immunoglobins (antibodies) – passive immunity
Advantages / Disadvantages of Breastfeeding
Advantages
1) Health benefits for baby and mother
2) Bonding
3) Convenience / expense
Disadvantages
1) Cracked / sore nipples
2) Mastitis (breast tissue infection)
3) Transfer of illness
Low Birth Weight (LBW)
A birth weight of less than 5.5 pounds – indication of vulnerability in new born
Small for Gestational Age (SGA)
A newborn who weighs less than they should
Highest and lowest percentage of newborns weighing less than 2,000 grams is where?
Highest: Turkey
Lowest: Iceland
Infant Mortatlity
Deaths of children less than one year of age
Highest and lowest infant mortality rate is where?
Highest: Mexico
Lowest: UK
Leading cause for infant mortality?
Congenital malformations
Apgar Scale
Activity Pulse (over 100 bpm) Grimace (reflex irritability) Appearance (skin color) Respiration
0-2 points are given to each
healthy baby = 10 points
When is the apgar scoring system used?
1 and 5 minutes after birth
1 in _ US births are a c-section
3
Newborn morality rate is 1 in __
250
Behavioral teratogens
agents and conditions that can harm the prenatal brain, impairing the future child’s intellectual and emotional functioning
What does it mean when we say that some teratogens have a threshold effect
when a teratogen is relatively harmless in small doses but becomes harmful when it reaches a certain level
Fetal Alcohol Syndrome
a cluster of birth defects, including weird facial characteristics, slow physical growth and reduced intellectual ability
Later in pregnancy, alcohol is a behavioral teratogen
Why is it that there is different susceptibility for dizygotic twins?
Because one will be more affected by alcohol than the other.
The Y chromosome may make male fetuses more vulnerable to many problems, such as?
More likely to be spontaneously aborted
More likely to be stillborn
False positive
he result of a laboratory test that reports something as true when it isn’t
Very low birthweight (VLBW)
a body weight at birth of less than 3 pounds, 5 ounces
Extremely low birthweight (ELBW)
a body weight at birth of less than 2 pounds, 3 ounces
Preterm
a birth that occurs 3 or more weeks before the full 38 weeks of the typical pregnancy
Immigrant paradox
the surprising paradoxical fact that low socio-economic status immigrant women tend to have fewer birth complications than native-born peers with higher incomes
Low socio economic status correlates with what?
low birth weight
What comes with low birth weight?
Every developmental milestone comes later (smiling, talking, walking, holding a bottle etc)
Cognitive difficulties
Visual and hearing impairments
w Lower IQ
Brazelton Neonatal Behavioral Assessment Scale (NBAS)
a test often administered to newborns that measures responsiveness and records 46 behaviors including 20 reflexes
Reflex
an unlearned, involuntary action or movement in response to a stimulus, occurring without conscious thought
How many pregnancies end in the death of the mother?
Less than 1 in 10,000
- A fine needle is inserted into the amniotic sac
- Under ultrasound guidance
- A sample of amniotic fluid, containing free-floating cells derived from the fetus, is removed
What is this procedure called?
Amniocentesis
cervical nerve roots coming out of C4-C7 get damaged
Results in Erbs Palsy of the right arm (becomes limp)
Brachial Plexus Injury
