Antepartum pt.1

Where does fertilization take place?

In the fallopian tubes, when the ovum and sperm unite. Occurs around 2 weeks after last normal menstrual period in a 28 day cycle.

How long does the fertilized egg take to travel to the uterus?

About $7\text{ to }10$\,days (roughly a week) before it implants in the endometrium.

Where does the fertilized egg implant?

In the endometrium of the uterus.

Around what days does implantation occur?

Around day $7$ to day $10$.

Who determines the sex of the baby?

The father, not the mother.

What can keep a fertilized egg from reaching the uterus?

Problems with fertilization, or structural damage to the fallopian tubes where the fertilized egg has to travel.

What are the three stages of prenatal development and their time frames?

1. Pre-embryonic: fertilization through week $2$

2. Embryonic: week $3$ to week $8$

3. Fetal: week $9$ until delivery

What happens during the pre-embryonic stage?

Fertilization occurs, cell division and differentiation happen, and implantation takes place around day $7$ to $10$.

What structures begin forming during the embryonic stage?

The embryonic layers of ectoderm, mesoderm, and endoderm germ layers, as well as the amnion (inner layer), chorion (outer layer), and amniotic fluid. Those are going to help the fetus grow and protect it. The development of organs and body systems begins rapidly.

What develops from the endoderm layer?

The beginnings of the digestive system, liver, pancreas, and lungs.

What develops from the mesoderm layer?

The circulatory system, skeletal system, and muscular system.

What develops from the ectoderm layer?

Hair, nails, skin, and the nervous system.

When is the developing baby MOST susceptible to teratogens?

During the embryonic stage (weeks $3$ to $8$), when organ systems are starting to develop.

Why is the embryonic stage especially risky in real life?

Weeks $3$ to $8$ is a timeframe when many women do not yet know they are pregnant, so they may not avoid harmful exposures or obtain adequate nutrition. Anything that mom ingests, inhales, or is exposed to can adversely affect fetal development. During stage the fetus is most susceptible to TERATOGENS.

What is a TERATOGEN?

Any substance or agent that can cause malformations or abnormalities in a developing fetus.

What begins forming around week 3 of embryonic development?

The brain, spinal cord, heart, GI tract, and arm and leg buds.

What milestone happens at week 5?

The heartbeat becomes a regular rhythm.

What milestone happens at week 6?

Formation of the lungs begins.

What milestone happens around week 7?

The heartbeat can be heard on ultrasound (confirming pregnancy); lips, mouth, and early tooth buds form.

What milestone happens at week 8?

Facial features develop and heart development is complete. Resembles a human.

What defines the fetal stage?

Week $9$ until delivery. All major organ systems are present in basic form, followed by dramatic growth and refinement.

How long is a full-term pregnancy?

$40$\,weeks.

When can fetal gender usually be determined?

By about week $12$.

What is quickening, and when does the fetus start moving?

Quickening is the mother feeling fetal movement (often felt like butterflies). The fetus starts moving between weeks $13$ and $16$.

When can the fetal heart rate be heard with a stethoscope?

Between weeks $17$ and $20$.

What is vernix caseosa and what does it do?

A white, cheese-like substance that coats the fetus around weeks $17$ to $20$ to moisturize and protect skin in amniotic fluid.SInce the baby is floating in a bag of water essentially, it protects the baby from amniotic fluid and helps prevent skin damage.

What is lanugo?

Fine hair covering the fetal body (trunk, shoulders, back) that begins disappearing around weeks $33$ to $38$.

What is the period of fetal viability?

About $24$ weeks — the earliest gestational age at which a baby can generally be delivered and survive.

What happens in the lungs during weeks 21 to 24?

Alveoli form and surfactant production begins.

What is the primary function of surfactant?

It decreases surface tension in the alveoli to prevent them from collapsing, enabling gas exchange.

Why are weeks 21 to 24 crucial for fetal survival?

Because alveoli and surfactant develop during this window, making gas exchange questionable, and baby is going to have alot of respiratory issues.

What happens during weeks 29 to 32 regarding respiration?

Rhythmic breathing movements of fluid occur (oxygen exchange still takes place via the umbilical cord).

What developmental milestones occur during weeks 33 to 38?

Testes descend, lanugo begins to disappear (sometimes the baby will be born with these hairs, but it will eventually go away, and maternal antibody transfer takes place.

What gestational age range is considered full term?

$38\text{ to }40$weeks.

When baby’s are in the uterus, they are no breathing air

but instead rely on the placenta for oxygen through the umbilical cord, leading to fluid-filled lung movements. The fetal circulations looks different because we want to shunt blood away from their lungs.

What are the three fetal shunts and what does each bypass (pushing blood away from lungs)?

1. Ductus arteriosus: bypasses the lungs

2. Foramen ovale: bypasses the lungs and left ventricle

3. Ductus venosus: bypasses the liver

These shunts allow blood to mainlu go to the baby’s body and organ systems

Why does the fetus require circulatory shunts in utero?

The lungs and liver do not perform full metabolic/respiratory functions in utero; oxygenation occurs in the placenta.

When do the ductus arteriosus (lungs) and foramen ovale (L. Ventricle and Lungs) normally close?

Right after birth (within hours to about a day).

How long does the ductus venosus (liver shunt) take to close after birth?

Between $2$ and $13$,days.

What does PDA and PFO stand for and mean?

Patent Ductus Arteriosus and Patent Foramen Ovale — failure of the shunt to close after birth, causing abnormal blood flow and not bypassing oragans we need to bypass.

What assessment finding suggests a fetal shunt failed to close?

A cardiac murmur heard upon auscultation of the infant.

How are unclosed fetal shunts treated?

Monitoring for spontaneous closure, pharmacologic therapy, or surgical repair.

Shunts not closing in preterm infants is seen a lot of times and…

pulmonary pressures and complications can occur, and respiratoy effor is very poor.

Why do preterm infants frequently develop physiological jaundice?

Their liver is immature because the delayed closing of the ductus venosus and cannot efficiently process and conjugate bilirubin.

What changes occur at birth to transition the infant to normal adult circulation?

The first breath expands the lungs, cord clamping stops placental blood supply, shunts close, systemic vascular resistance increases, and the liver activates.

Where does fetal gas exchange and oxygenation occur?

In the placenta.

What is amniotic fluid and how much is present at term?

A fluid-filled sac surrounding the fetus that increases up to approximately $1$liter (1000\n,mL ) by term.

What is amniotic fluid composed of?

Maternal blood plasma and fetal urine (roughly $90\%$ water and $2\%$ organic matter).

What are the key functions of amniotic fluid?

Thermoregulation (homeostasis), enabling symmetric growth, cushioning against physical trauma, preventing umbilical cord compression, and promoting fetal movement.

How does amniotic fluid maintain thermoregulation?

It maintains a stable, homeostatic ambient temperature regulated by maternal body heat.

Why is amniotic fluid required for symmetric fetal growth?

It provides space for the fetus to float and move, allowing equal growth of musculoskeletal and internal structures.

What is oligohydramnios?

An abnormally low volume of amniotic fluid, typically less than 500\n,mL at term. (half of what we would want normally to have)

What complications are associated with oligohydramnios?

Uteroplacental insufficiency, umbilical cord compression (baby compresses on that cord and possibly cut off circulation), fetal deformities, and pulmonary hypoplasia.

What is a uteroplacental insufficiency?

A condition where the placenta fails to deliver adequate oxygen and nutrients from the mom to the fetus, leading to potential growth restriction and other complications.

What is pulmonary hypoplasia?

Underdevelopment of lung tissue resulting in incomplete lung structure and function.

What is polyhydramnios?

An excessive volume of amniotic fluid, typically approaching or exceeding 2000\n,mL ($2$\,liters). (Double than normal)

What complications are associated with polyhydramnios?

Preterm labor, fetal macrosomia (big baby), umbilical cord prolapse, prolonged labor, uterine atony (uterus doesn’t contract), and premature rupture of membranes (PROM).

What is fetal macrosomia?

An abnormally large fetus, often defined as birth weight greater than 4000\n,g or 4500\n,g.

What is umbilical cord prolapse and why is it an emergency?

The umbilical cord slips past the presenting part into the vagina before delivery, leading to cord compression and fetal hypoxia.

What does PROM stand for?

Premature Rupture Of Membranes.

How many blood vessels are contained in a normal umbilical cord?

Three vessels: one vein (carrying oxygenated blood to fetus) and two arteries (carrying deoxygenated blood away).

What is Wharton's jelly?

A gelatinous (whitish-yellow) protective connective tissue surrounding and cushioning the umbilical cord vessels. Squishy inside mom and drys out outside.

What is the typical size and growth timeframe of the umbilical cord?

It finishes growing by about $30$\,weeks, reaching up to $22$\,inches in length and $1$\,inch in diameter.

What is the primary function of the umbilical cord?

To serve as the vascular conduit for oxygen, nutrients, and waste exchange between placenta and fetus.

How does cord appearance differ between healthy and compromised pregnancies?

Healthy cords are plump and firm ("juicy"), whereas compromised cords (e.g., from maternal smoking, hypertension, poor nutrition) appear thin, skinny, or discolored.

What is the placenta and what are its main functions?

A temporary fetomaternal organ that facilitates oxygen/nutrient delivery, waste removal, hormone production, and maternal energy storage.

What happens to the placenta after delivery of the infant?

It detaches from the uterine wall and is expelled during the third stage of labor.

What is the placental barrier?

A tissue layer separating maternal and fetal blood circulation while permitting selective nutrient, gas, and waste exchange via diffusion.

What harmful substances can cross the placental barrier?

Drugs, medications, alcohol, and certain pathogens/viruses.

Why is the placental barrier essential?

To keep maternal and fetal blood separate, preventing direct immune rejection or antibody destruction of fetal RBCs.

What is "Shiny Schultze"?

The smooth, shiny, grayish fetal side of the placenta.

What is "Dirty Duncan"?

The dark, beefy-red, highly vascular maternal side of the placenta that attached to the uterine wall.

What is the function of hCG (human chorionic gonadotropin)?

It signals pregnancy (detected in pregnancy tests) and maintains the corpus luteum to produce progesterone early on.

What is the role of progesterone during pregnancy?

It induces uterine smooth muscle relaxation, promotes placental growth, and stimulates breast development.

Why is uterine relaxation necessary during pregnancy?

To suppress uterine contractions and prevent preterm labor while the fetus develops.

What is the role of estrogen during pregnancy?

It promotes uterine tissue growth, fetal organ development, breast tissue expansion, and prepares the body for labor.

What is the function of relaxin?

It inhibits uterine contractions and softens pelvic ligaments and joints to facilitate childbirth.

What is the function of prolactin?

It stimulates mammary gland growth and initiates milk production.

When does the placenta take over hormone production from the corpus luteum/ovaries?

Around weeks $6$ to $7$ of pregnancy.

What is a teratogen?

Any agent, drug, virus, or environmental factor that causes structural or functional birth defects or fetal death.

When are Teratogens the most harmful to the fetus?

During the embryonic period, specifically from weeks $3$ to $8$ of pregnancy. This is when the foundational organ systems are developing and the fetus is particularly sensitive to harmful agents.

What are common examples of maternal teratogens?

Ionizing radiation, heavy metals (mercury, lead), TORCH infections (toxoplasmosis, rubella, CMV, herpes, varicella), high-dose vitamin A, certain anticonvulsants, and anticoagulants.

Why is Accutane (isotretinoin) contraindicated in pregnancy?

It contains high levels of vitamin A derivatives, which cause severe craniofacial, cardiac, and CNS birth defects. You have to show them u have two different types of birth controland must have a negative pregnancy test before using it and are not trying to get pregnant, due to its high risk of severe fetal harm.

What is the source of Toxoplasmosis and how can pregnant women avoid it?

Cat feces/litter and undercooked meat; pregnant women should delegate litter box cleaning and handle raw meat carefully.

What dietary source poses a high risk of fetal mercury exposure?

Certain large predatory fish and shellfish high in methylmercury.

What are the three clinical classifications of pregnancy signs?

1. Presumptive

2. Probable

3. Positive

What are common presumptive signs of pregnancy?

Amenorrhea (missed period), fatigue, breast tenderness/enlargement, Uterus enlargement, urinary frequency, nausea/vomiting, and maternal quickening (movement in lower abdomen0.

Why are presumptive signs considered inconclusive?

They are subjective symptoms experienced by the woman that can be caused by conditions other than pregnancy.

What are common probable signs of pregnancy?

Positive pregnancy test, ballottement (return of the fetus when tapped), Braxton Hicks contractions, uterine enlargement, and Goodell's, Chadwick's, and Hegar's signs.

What is ballottement?

A physical exam technique where upward pressure on the cervix causes the unengaged fetus to float upward and tap back down.

What is Goodell's sign?

Softening of the cervix observed during pelvic examination.

What is Chadwick's sign?

A bluish-purple discoloration of the cervix, vagina, and labia caused by increased vascularity.

What is Hegar's sign?

Softening of the lower uterine segment (isthmus).

Why is a positive pregnancy test classified as a probable rather than positive sign?

Elevated hCG levels can occasionally be produced by conditions other than normal pregnancy, such as molar pregnancy or hCG-secreting tumors.

What are the positive signs of pregnancy?

1. Fetal heartbeat visualized on ultrasound

2. Fetal heartbeat auscultated by clinician

3. Fetal movement felt by examiner (20 weeks)

4. Direct ultrasound visualization of fetus

How do quickening and clinician-palpated movement differ in sign classification?

Quickening is a subjective maternal feeling (presumptive), whereas movement felt by a clinician is an objective verification (positive).

What is the diagnostic significance of hCG in pregnancy detection?

It is the primary biochemical marker produced by trophoblastic cells that triggers positive urine/blood pregnancy tests.

How do hCG levels normally progress in early pregnancy?

They double every $48\text{ to }72$\,hours, peak around $10\text{ to }12$\,weeks, and then plateau.

What do low or abnormally dropping hCG levels indicate?

Impending miscarriage or an ectopic pregnancy.

What do abnormally high hCG levels suggest?

Multiple gestation (twins/triplets) or a gestational trophoblastic disease (molar pregnancy).