Conception and Fetal Development Flashcards
Fertilization occurs when and where?
It occurs when there is a union of the nuclei of the sperm and ovum.
Location is in the outer third or ampulla of the fallopian tubes.
How long is the ovum fertile for?
How long can sperm survive? Fertile time phrame?
24 hours
Sperm can survive for 48-72 hrs.
Sperm are only fertile tho for 24 hrs as well.
(Sperm information contradicts her previous notes from family planning????)
So when the egg is released from the ovary & taken up into the fallopian tube - how does it move, again?
Ciliary movement and current pushes it along
How does the sperm move in order to meet the ovum?
Sperm have a tail that helps them move.
How many sperm should penetrate an ovum?
Which is bigger - ovum or sperm?
One sperm per ovum typically
The ovum is much bigger.
How is it that only one sperm can enter the ovum?
Zonal reaction or ability of the membrane to block other sperm.
What is conception?
What do the chromosomes do?
Formation of the zygote
The chromosomes then pair up. XX or XY
What does the zygote form into officially? And where does this formation burrow?
What is this process called? How many days should this take?
The zygote will form into the blastocyst.
And then the blastocyst will burrow into the endometrium - which is the inner lining of the uterus.
Process is known as implantation. Takes between 6-10 days.
What is the best site for implantation?
What name change occurs of the endometrium after implantation?
The side or posterior wall. NOT the front.
The endometrium or inner lining will have its name changed to decidua.
What is the site of implantation of the decidua (new name for endometrium)? What is it?
Decidua capsularis
It is a bubble structure that covers the blastocyst
What is is the maternal side of the placenta?
Decidua basalis. It serves as the base for the placenta.
What is the Decidua vera?
Remaining uterine lining of the decidua/endometrium that really isn’t all that affected by pregnancy.
Why are twins becoming more common?
Due to delayed child bearing and artificial reproductive treatments
Two types of twins?
Dizygotic
Monozygotic
Dizygotic twins
How many ovum and sperm needed?
How many placentas, chorians, amnions?
Two of everything because they are totally separate.
Will dizygotic twins always be the same gender?
No, these twins can be separate genders bc they’re separate in general.
What increases chances of having Dizygotic twins?
These twins are pretty much separate fyi…
Older pregnancy
Familial genes - twins tend to run in families
Going off the pill & having multiple ovum released.
Obesity
Monozygotic twins
Will have how many ovum and sperm?
How many placentas?
Will these be identical twins? Gender?
Will have one single fertilized ovum (so one sperm).
One shared placenta.
Yes - they are identical. Same gender as well.
Risk of monozygotic or identical twins?
What type of treatment could increase this?
Can become conjoined or have Siamese twinning where they are fused.
ART or artificial
Which types of twins will do better?
The Dizygotic twins will do better since they have their own stuff.
Monozygotic babies share placenta and possibly their chorion. Baby A gets the nutrients and Baby B is second.
Will blood ever be shared/mixed between mom and baby?
No - two separate circulatory systems going on. Unless there’s trauma and a vessel ruptures.
What do babies do to amniotic fluid that surrounds them?
They recycle it by drinking and peeing in it.
Cotyledons of placenta
Beefy red sub-sections of placenta
Fetal side of placenta
Where cord comes off of and attaches to the fetus.
Shiny, gray color
How big is the placenta at 20 weeks
How big is it by term
Covers 1/2 of uterine surface
By term it is 6-9 inch diameter and about 1 Ib
What if a mom is Rh-?
There could be mixing of blood due to maternal antibodies if baby is positive (it’s a blood type)
While there shouldn’t really be any mixing of blood unless there is something rare or abnormal - can the mother’s circulation affect the baby in any way?
Yes. Maternal circulation can increase or decrease uterine blood flow. Same thing can happen with mother’s blood pressure.
Ex: hypertension can decrease the CO and thus uterus &. placenta aren’t perfused doesn’t get enough
Uterine souffle
Listening over to maternal blood vessels which is the pulse of the mother. Whoosh noise.
Funic souffle
To listen to HR over umbilical cord that equals FHR - but you don’t want to necessarily listen to this.
Do it over the baby’s back.
What does the placenta transport?
How does the placenta act as the lungs?
Nutrients
Waste
Antibodies the last month of pregnancy/mother’s gift/passive immunity
Takes care of gas exchange components like O2 and CO2
Major hormones from placenta
hCG - basis of pregnancy testing; found in blood & urine
hPL - metabolism & growth in pregnancy
Estrogen - growth hormone of breast, uterus, blood
Progesterone - keeps uterus quiet and calm
Dirty duncan presentation
When placenta presents maternal side up with the Cotyledons
Where should the cord be on the placenta
In the center - unless there is an abnormality
Umbilical cord contains how many arteries and veins
acronym?
2 arteriers
1 vein
AVA - arteries on side and vein in center
Umbilical artery
Umbilical vein
Takes deoxygenated blood to placenta
Takes oxygenated blood to to the fetus
so reverse of your circulation
Percent of umbilical cords that only have 1 artery and 1 vein?
1%
The baby will still be healthy - but want to take a closer look to make sure there aren’t any other issues.
Does it hurt the baby when you cut the cord?
No - there’s no pain receptors.
How long is the cord?
Why does the length matter?
Same length of baby so 20-22 inches
If the cord is too short then it can get too tight and seperate
Protein around the umbilical cord?
What does the high blood volume help with?
Wharton’s Jelly - gelatin substance and water. Cushions the vessels.
Will fall off after delivery
It can keep the cord from tangling up around baby neck or having a nuchal cord. Can kill the baby
Ultrasound and doppler blood flow study helps with what?
Complications of pregnancy. Can check for blood flow through the vessels
Amniotic sac or Bag of water layers (2)
Are they fused together?
Amnion or inner layer that develops from the blastocyst. It is thin,
Chorion or outer membrane of the sac. Develops from the trophoblast and is thick.
No, they are not fused together.
Amniotic fluid amount at 39 weeks?
Amount at 41 weeks?
Main point?
700-900 mL
500 mL
So - this is why we never want a pregnancy to go past 40 weeks bc the amniotic fluid decreases.
Polyhydraminos
Excessive amount of amniotic fluid greater than 2L
Why would a baby have too much amniotic fluid (polyhydraminos)?
Gi issue like esophageal problem where baby can’t swallow their own amniotic fluid and so the fluid never gets recycled. It just accumulates in the sac.
Other reason is there could be more than one fetus and so more fluid is needed.
Diabetes - glucose can transfer to baby and the baby enlarges but also pees out everything so the fluid accumultes
Oligohydramnios
Not enough amniotic fluid so like less than 300 mL
Fluid will be super concentrated
half of the normal amount too
Why would a baby have Oligohydraminos or not enough fluid in their amniotic sac?
Since the fluid is recycled -
baby may not be excreting fluids due to kidney issues
Maternal drug use can cause no kidney in child
Or Reduced blood volume so less fluid
Or post date PG so 41 weeks
Amniotic fluid ph ?
Alkaline or high ph
What will amniotic fluid look like
full of cellular debris so cloudy but may come out clear
What if amniotic fluid is red?
What if fluid is green?
Means there could be bleeding
Green could be stool or meconium
Three sources of amniotic fluid?
Amnion cells
fetal urine
fetal lungs
How to diagnose amount of amniotic fluid?
Fundal height . After 20 weeks - the weeks represent height.
So 21 weeks = 21 cms.
Sonogram by measuring AFI - amniotic fluid index or measurement of parts of placenta (5-18 is normal .. 26 is high)
subjective data - does the mother think her pregnancy is weird? Especially compared to other pregnancies?
Amniosythesis
Analyze amniotic fluid by drawing out fluid from sac.
Can determine gender, chromosomal info.. etc. Maturity.
How does amniotic fluid help with pressure?
It surrounds the fetus equally and keeps the pressure equal to develop normally
How does amniotic fluid help with movement?
It creates a gravity free environment for the baby to move and float around - which also helps muscles.
What does amniotic fluid help prevent?
Prevents fetus from sticking to the amnion sac.
How does amniotic fluid control temp?
Well the baby will feel your temp so regulates constant body temp.
If you’re cold - your baby will be cold. If hot - they will be too.
Do babies swallow amniotic fluid?
Yes - it their source of oral fluid.
And they excrete their urine. It is sterile tho.
Why do the placenta and amniotic fluid have to manage fluids and electrolytes?
A fetus doesn’t have adequate kidneys and so the placenta and amniotic fluid take care of it.
How does amniotic fluid affect lungs
Baby has to have amniotic fluid bc it helps with practice breathing in utero. Without it, baby can die when it’s birthed. Chest wall movement practice
The amniotic fluid pushes against the cord.
If there isn’t enough - symptoms of oligohydramnios occur. What is this evidenced by?
Variable decelerations in HR
How does amniotic fluid act as an intact bag?
Dilating wedge against the cervix in labor
However, often they’ll rupture the membrane of placenta to allow baby’s head to be the dilating wedge since its much harder.
Order of fetal progression
zygote> blastocyst > embryo> fetus
Embryo weeks
What develops in this time frame?
2-8 weeks
Organs
After 9 weeks ?
Fetus
Fetal development week 4 of the heart
Heart is beating at 28 days & circulating blood
What does a week 5 embryo look like in shape?
a C shape
Fetus at week 9?
Every organ system and external structure is present
Fetus at week 12
What does the HR do as pregnancy ensues?
Resembles a human
Fetal heart tones can be heard , 120-160 usually
The HR will slow
Fetus at week 16 development
The sonogram can now try to pick up whether a fetus is a boy or girl
Fetus at week 20
Activity such as quickening is felt by the mom
Vernix (cheesy coating)
Lanugo (peach fuzz like growths on body)
FHR is heard by a fetoscope
Fetus at week 24
Skin is now COVERED by vernix
Alveolar ducts and sacs are present with no surfactant
Lethicin begins showing up by 27 weeks! (can survive outside of uterus)
Fetus at week 28
Lungs can now do mature gas exchange
Eyelids open
Fetus at 36-40 weeks
weight
Lanugo and Vernix?
Genitals?
immunnity?
More weight gain due to subcutaneous fat
Lanugo and vernix begin to disappear
Testes descend to scrotum
Labia majora becomes more full to cover up other parts of vagina due to fat deposits from weight gain
Mother’s anitbody gift transfer complete
Teratogen
Agent that can cause an abnormality in fetus structure
drugs
virus
radiation
First system to function in embryo?
Circulatory system
What determines a baby’s blood type
Parent genes
How is that babies carry more O2 than adults
due to larger fHGB - which protects against hypoxia
Will a baby or mother have more fHGB?
Baby
If a baby’s FHR is higher than a humans, does that increase or decrease CO?
Will increase CO!
Will an adult or baby have a higher pulmonary bp?
Baby bc of pulmonary vessel constriction & thus blood is diverted from lungs all together?
How is that blood is able to flow back to the placenta in a fetus?
Fetal systemic pressure is just lower
Ductus venosus
Shunt that helps bypass the liver in fetus since it is underdeveloped
Ductus arteriosis
A different shunt which is between the Pulmonary and artery in order to drive blood from lungs to systemic circulation
Foramen ovale
ASD?
Shunts blood from right atrium to left atrium via a small hole in heart
Eventually this will be covered again by a flap but if not, then you have an atrial septal defect
At 24 weeks can the aveoli produce surfactant?
no. But the alveioli are present
Then when can surfactant be produced?
important surfactant ratio?
28-32 weeks to ease breathing so alveoli dont stick together
Lecithin : Spinogomyelin
2:1 means mature lungs for breathing and this finally occurs around 35 weeks
Conditions that accelerate lung development
Fetal stress Maternal hypertension Infections Steriods (might be giving these for pre-term labors 24-34 weeks) Placental dysfunction
Conditions that delay lung development
Maternal diabetes
Maternal renal problems
These issues can cause a baby to be bigger than what the maternal week development shows. So, size does not determine maturity whatsoever.
How can Oligohydramnios inhibit lung development?
It can cause there to be less fluid for the baby to able to practice breathing and so lungs don’t develop as well.
Why would a C-section baby have more fluid in lungs upon birth?
A vaginal birth squeezes the fluid out of the baby as to facilitate its first breathe.
A c-section baby doesn’t experience that squeezing and so the fluid remains. Will have resp. distress until fluid is suctioned out or absorbed maybe 24 hrs.
How do babies develop first ?
Proximal -distal
Head to toe
How does oligohydramnios affect the musculture?
Inhibits normal development
contractures
deformities
If you feel the baby move is this good or bad?
Good. Once you start to feel the quickening, you’ll want to feel this almost every day thereafter
How often do babies sleep in the womb?
Every 20 min. It is a sleep wake cycle
Will the vernix caseosa or cheesy coating increase or decrease as fetus gets closer to term? What about lanugo?
Decrease for both of them.
So if the baby is cheesy upon birth, that means it was an earlier labor than 40 weeks. Same with lanugo.
Will fingernails or toenails develop first?
Fingernails first
Toenails second
Cephalocaudal development
Can babies suck and swallow in PG?
When will a baby develop a gag reflex?
Yes!
8 months for protection
Meconium
What if there is a passage that occurs in utero? Why can this be bad?
Tarry black green stool in NB. Will transition to yellow brown & stay yellow.
Could indicate maturity or means they’re hypoxic. If they become hypoxic to the point of apoxic - they can have anal sphincter relaxation which causes the utero poop.
Need to consider if maturity or stress.
What is a meconium breech presentation?
meconium stained liquid on butt.
Should be head down for labor.
How soon should a baby have meconium passage after birth?
What if they don’t?
48 hrs
Could indicate an imperforated anus that is not patent.
Will need surgery
or could be from meconium illeus due to cystic fibrosis due to it being in the family
What week if urine formation started?
12 weeks - but it’ll be a small, clear amount, no smell
How can a fetus have acid base balance issues very quickly?
Kidneys aren’t doing the excretion in this case.
How soon should a baby urinate after birth?
Within 24 hrs
Main function of the liver during PG?
Glycogen stores
Iron stores - if you’re anemic, after 5-6 months infant can develop anemia since theirs will be depleted
Can a baby break down bilirubin ?
Not very well due to immature liver. They may develop jaundice - and we assess during first week of life.
What does a baby’s sterile gut contribute to?
Cannot produce vit k and so all newborns receive an IM injection within 2 hrs of delivery
Vit k = keeps them from bleeding
How should a mom control fetal metabolism?
Avoid hot environments that may make her hot or over heat ; hyperthermia
If not controlled can lead to dna synthesis issues.
Brown fat
Fat the baby is born with
We metabolize it to produce heat
White fat
Layer of insulation between skin and blood vessels - laid down last month of pregnancy. Keeps them warm and adds pink color to skin.
How can some babies develop congenital hypothydroism? Is this more common than hyper?
They don’t produce thyroxine.
Can be either but hypo more often.
But babies need to be screened for thyroid function.
When is the pancreas able to produce insulin?
What does Macrosomnia mean?
20 weeks
Big bodied baby
Glucose can cross the placenta and now the baby can store it - and they end up huge. Latter part of pregnancy . common in hyperglycemic moms
What is passive immunity?
Gift to baby from mother in IGG
Keeps baby healthy for about 6 months
Largest group of antibodies that crosses the placenta?
IGG
the gift antibody
Antibodies from breatfreeding?
What systems does it help?
IGA
GI, GU and respiratory system from infection
What antibodies are produced by the fetus?
IGM
will test this if they suspect sepsis
