Week 14: Conception, Pregnancy, and Fetal Development Flashcards
What is fertilization?
When a sperm and an oocyte (egg) combine and their nuclei fuse to make a zygote
What is a Haploid cell?
A haploid cell contains half of the genetic material to make a human
What is a Diploid cell?
A diploid cell contains all genetic material needed to make a human
Sperm (haploid) + Oocyte (haploid) = ?
Zygote (diploid cell)
When are sperm released?
During ejaculation
Though there are millions of sperm ejaculated, what prevents most of them from entering the uterus?
The acidity of the vagina (pH ~3.8) and thick cervical mucus
How long can it take sperm to reach the Uterine tubes?
It can take 30 minutes to 2 hours
How long can sperm survive in the Uterine tubes?
They can survive in the Uterine tubes for 3-5 days
How long can an Oocyte (egg) last after ovulation?
Only approximately 24 hours
What is Capacitation (priming)?
Fluids in the female reproductive tract prepare the sperm for fertilization through a process called capacitation, or priming.
Why does Capacitation occur?
It improves the motility of the spermatozoa and depletes cholesterol molecules embedded in the membrane of the head of the sperm to help facilitate release of lysosomal (digestive) enzymes needed to penetrate oocyte’s exterior
Why must sperm undergo Capacitation?
Sperm must undergo the process of capacitation in order to have the “capacity” to fertilize an oocyte.
What happens if sperm reach the oocyte before they undergo Capacitation?
If sperm reach the oocyte before capacitation is complete, they will be unable to penetrate the oocyte’s thick outer layer of cells.
Why must fertilization occur in the distal uterine tube?
An unfertilized oocyte cannot survive the 72-hour journey to the uterus.
What are the 2 layers a sperm cell much penetrate to reach the oocyte?
- Corona radiata
- Zona pellucida
When sperm penetrate the layers of the oocyte, what does it initiate?
The acrosomal reaction
What is the acrosomal reaction?
A process where the enzyme-filled “cap” of the sperm, called the acrosome, releases its stored digestive enzymes.
What do the enzymes from the acrosomal reaction do for the sperm?
The enzymes clear a path through the zona pellucida that allows sperm to reach the oocyte; a single sperm then can make contact with the sperm-binding receptors on the oocyte’s plasma membrane
What is Polyspermy?
Penetration by more than one sperm
What happens to the zygote if more than one sperm fertilize the oocyte?
The resulting zygote would be a triploid organism with three sets of chromosomes, which is incompatible with life
What are some mechanisms to prevent Polyspermy?
Fast block (immediate response)
Slow block (cortical reaction)
What is a Fast Block?
Within seconds, penetration of sperm leads to a change in egg membrane depolarization (+ charge), prevents further sperm entry, lasts ~1min (temporarily blocks sperm)
What is a Slow Block?
Within minutes,
Ca²⁺ release → Cortical granule exocytosis → Hardening of zona pellucida/fertilization membrane, it is a permanent sperm block
The two haploid nuclei derived from the sperm and oocyte and contained within the egg are referred to as _____.
Pronuclei
What happens with the Pronuclei?
The pronuclei migrate toward each other, their nuclear envelopes disintegrate, and the male- and female-derived genetic material intermingles.
What happens after the male- and female-derived genetic material intermingles?
This step completes the process of fertilization and results in a single-celled diploid zygote with all the genetic instructions it needs to develop into a human.
What are Fraternal twins (dizygotic)?
Two eggs are released and both are fertilized; two zygotes form, implant, and develop, resulting in the birth of dizygotic (or fraternal) twins
How identical are Fraternal twins?
Because dizygotic twins develop from two eggs fertilized by two sperm, they are no more identical than siblings born at different times.
What are Identical twins (monozygotic)?
A zygote divides into two separate offspring during early development
What happens if a zygote splits at the two-cell stage?
The embryos will have individual placentas
What happens if a zygote splits at the early blastocyst stage?
The embryos will share a placenta and a chorionic cavity
What is the Chorionic Cavity?
A fluid-filled space that surrounds the developing embryo
What are the 3 stages following conception?
- Pre-embryonic
- Embryonic
- Fetal
How long is the Pre-embryonic stage?
Weeks 1-2 after conception
How long is the Embryonic stage?
Weeks 3-8 after conception, after this stage all organ systems are structured
How long is the Fetal stage?
Weeks 9 through to birth
After fertilization in the Uterine tubes, where does the zygote go?
The zygote and its membranes (conceptus) moves toward the uterus via peristalsis and cilia in the fallopian tubes.
What happens to the zygote during its journey to the Uterus?
The zygote undergoes 5-6 rapid mitotic divisions called cleavage, producing daughter cells called blastomeres.
After 3 days, the zygote reaches the uterus and is how many cells?
It is a 16-cell conceptus
The cells that had been loosely grouped are now compacted and look more like a solid mass called a ______.
Morula
In the uterus free floats for days while dividing until it is approximately how many cells?
100 cells
What does the ball of cells consume while it is free floating in the uterus?
It consumes nutritive endometrial secretions called uterine milk while the uterine lining thickens for its implantation
What is the conceptus referred to as at this developmental stage?
A blastocyst
The inner cells of the blastocyst are totipotent, which means what?
Each cell has the potential to differentiate into any cell type in the human body, meaning they will become the embryo
The outer cells of the blastocyst are called trophoblasts which means what?
They will become the chorionic sac and the fetal portion of the placenta
As the blastocyst forms, the trophoblast excretes enzymes that begin to do what?
Degrade the zona pellucida
What happens in the process called “hatching”?
The conceptus breaks free of the zona pellucida in preparation for implantation
The pre-embryonic cleavages of 2-cell, 4-cell, and 8-cell occur where?
In the Uterine tubes
The pre-embryonic cleavages of Morula and Blastocyst occur where?
In the Uterus
When does Implantation occur?
The end of week 1
How does Implantation occur?
The blastocyst adheres to the uterine lining via the trophoblast cells
Where is the Implantation site?
Usually in the fundus or posterior uterine wall
Why might the Blastocyst fail to implant?
If the endometrium is not ready, the blastocyst may detach and relocate
T or F: 50–75% of blastocysts do not adhere and shed during menses
True, pregnancy often requires multiple cycles because of the high failure rate
In week 2, following a successful implantation, what begins?
Syncytiotrophoblast Formation
What occurs during Syncytiotrophoblast Formation?
Outer layer of trophoblast cells fuse into a multinucleated body, and digests uterine endometrial cells to secure the blastocyst to uterine wall.
What is the Uterine Response to Syncytiotrophoblast Formation?
Mucosa rebuilds and envelops the blastocyst.
What is Human chorionic gonadotropin (hCG) Secretion?
Secreted by syncytiotrophoblast to maintain the corpus luteum, it continues progesterone & estrogen production and prevents furtherovulation, menses & supports embryo development.
When is hCG detectable?
Present in blood (6-8days)and urine (12-14days) post implantation (basis for pregnancy tests).
What are some complications with Implantation?
Ectopic pregnancy
Placenta Previa
What is an Ectopic Pregnancy?
The embryo implants outside of the uterus
(1–2% of pregnancies)
Where might an Ectopic Pregnancy occur?
- Tubal: Implants in the fallopian tube
- Ovarian: Egg never leaves ovary
- Abdominal: Egg lost in travel or re-implants after tubal pregnancy
- Scar tissue from STIs can block or trap the embryo
How are Ectopic Pregnancies resolved?
About 50% of ectopic pregnancies resolve from bleeding-induced contractions, but late detection can require surgical repair
What is Placenta Previa?
Implantation in the lower uterus, causing the placenta to cover the os of the cervix, leading to complications like antepartum (before birth) hemorrhage
(0.5% of pregnancies)
What are the 4 Embryonic membranes that the Blastocyst cells will form?
- Amnion
- Yolk sac
- Allantois
- Chorion
What is the Amnion?
Protects and cushions the embryo (amniotic sac & fluid)
What is the Yolk Sac?
Provides nutrients and primitive blood circulation (weeks 2-3).
By week 4, it shrinks and focuses on blood and germ cell production.
What is the Allantois?
Contributes to the umbilical cord and urinary bladder formation.
What is the Chorion?
Key role in placental formation.
What occurs during Amnion Development?
Forms from epiblast cells around the amniotic cavity and fills with amniotic fluid (initially maternal plasma, later fetal urine).
What are the functions of the Amniotic sac and fluid?
It protects from trauma & temperature changes, allows movement, and aids in swallowing/breathing practice.
What happens to totipotency cells during Embryogenesis?
They transition from totipotency (all cell types) to multi potency (limited range of cell types)
What is a Primitive Streak?
It forms on the dorsal surface of the epiblast; cells migrate inward, forming three layers:
What are the 3 layers the Primitive Streak forms?
- Endoderm
- Mesoderm
- Ectoderm
What is the role of the Endoderm?
It replaces hypoblast and is adjacent to the yolk sac
What is the Mesoderm?
Middle layer, forms between endoderm & ectoderm
What is the Ectoderm?
A layer of remaining epiblast cells that do not migrate
What does the Endoderm become?
It becomes the epithelial lining of the gastrointestinal tract, liver, pancreas, and lungs
What does the Mesoderm become?
It forms skeleton, muscles, connective tissues, heart, blood vessels, and kidneys
What does the Ectoderm become?
It develops into the nervous systems (central & peripheral), sensory organs, epidermis, hair, and nails
What do Decidual Cells for the development of the Placenta?
Endometrial cells nourish the embryo during early development (Weeks 1–4).
When does Placenta Formation occur?
Develops from both embryonic and maternal tissues by Weeks 4–12, taking over nourishment.
What is the Umbilical cord?
Connects the fetus to the placenta
What do the Umbilical arteries do?
Umbilical arteries carry deoxygenated blood & wastes from the fetus.
What do the Umbilical veins do?
Umbilical vein carries oxygenated blood & nutrients to the fetus.
The Umbilical cord is surrounded by what?
By the Amnion
The Umbilical cord is filled with what?
Wharton’s jelly (mucous connective tissue)
The maternal portion of the Placenta develops from where?
Develops from the decidua basalis, the deepest layer of the endometrium.
What do Chorionic villi do for the Embryonic portion of Placenta development?
The finger-like structures penetrate the endometrium, making up the fetal portion of the placenta.
What do Cytotrophoblast cells do for the Embryonic portion of Placenta development?
They remodel the maternal blood vessels to increase blood flow around the villi.
What do Fetal mesenchymal cells do for the Embryonic portion of Placenta development?
They fill the villi, differentiate into blood vessels, including the three umbilical vessels (two umbilical arteries, one umbilical vein)
When does Placenta development finish?
It completes by Weeks 14–16 (embryonic to early fetal period).
What are the functions of the Placenta?
- Nutrition & Excretion: Transfers nutrients and removes wastes.
- Respiration: Facilitates gas exchange (O₂, CO₂).
- Endocrine: Produces hormones
How does blood flow occur through the Placenta?
Umbilical arteries carry deoxygenated blood from the fetus; Chorionic villi filter wastes and return clean, oxygenated blood through the umbilical vein.
What sort of exchange occurs from the mother to the fetus?
- Simple diffusion: Lipid-soluble substances (O₂, CO₂).
- Facilitated diffusion: Water-soluble substances (e.g., glucose).
- Active transport: Nutrients like amino acids and iron
Why is it important that the blood of the mother and fetus are separate?
- To prevent immune reactions.
- So cytotoxic T cells cannot attack the fetus which carries “non-self” antigens.
- Prevents fetal red blood cells from entering maternal circulation and triggering antibody formation (reducing the risk of hemolytic disease in an Rh− person’s first Rh+ fetus)
How are substances exchanged between mother and fetus?
Chorionic villi provide surface area for two-way exchange (nutrients, gases, wastes).
The exchange rate increases as villi become thinner and more branched
What happens to the exchange rate when villi become thinner and more branched?
It increases
What are some of the lipid-soluble substances that can pass through the placenta and pose risks to the fetus?
Alcohol, nicotine, barbiturates, pathogens
What can alcohol consumption during pregnancy do to the fetus?
It can cause fetal alcohol spectrum disorders (FASD), leading to malformations and cognitive issues
Why is Neurulation important?
It is essential for development of central nervous system (CNS)
What occurs during Neurulation?
- Neural Plate Formation: The ectoderm thickens to form the neural plate.
- Folding: The neural plate folds inward, creating neural folds and a neural groove.
- Fusion: The neural folds fuse to form the neural tube.
- Closure: The neural tube closes, forming the brain (anterior) and spinal cord (posterior).
What are the 4 steps of Neurulation?
- Neural plate formation
- Folding
- Fusion
- Closure
What occurs when the Neural crest cells differentiate?
They form sensory ganglia and autonomic neurons
Why is Folate important for Neural Tube development?
Folate is essential for neural tube closure.
What defects may a Folate deficiency early in pregnancy lead to?
- Spina bifida: Spinal tissue protrudes through an incomplete vertebral column.
- Anencephaly: Partial or complete absence of brain tissue
When does Organogenesis occur?
Weeks 1-8
How does the heart initially form?
It initially forms as a tube-like structure
When does electrical conduction and contraction occur?
It starts early with beating beginning in Week 4 and blood pumping in Week 5 (with the liver temporarily producing red blood cells).
What happens during Organogenesis in Weeks 4-5?
Eye pits form, limb buds appear, and pulmonary system rudiments form.
What happens during Organogenesis in Week 6?
- Uncontrolled fetal limb movements.
- Intestines temporarily loop into the umbilical cord due to rapid development of the gastrointestinal system.
- Fingers and toes develop through apoptosis (tissue between fingers/toes disintegrates).
What happens during Organogenesis in Week 8?
Head nearly as large as the body and major brain structures are formed.
What is Ossification?
Bone begins to replace cartilage in the skeleton.
By the end of the Embryonic period, how big is the embryo?
Approximately 3cm (crown to rump) and 8 grams.
Which of the following substances can most readily pass through the placenta into fetal circulation?
a) Maternal blood
b) Fetal blood
c) Nicotine
d) Rh+ antigens
c) Nicotine
When does Sexual differentiation begin?
During weeks 9-12
T or F: Embryonic males and females, though genetically distinguishable, are morphologically identical.
True
What occurs during MALE fetal development?
Bipotential gonads become the testes and associated epididymis, Müllerian ducts degenerate, Wolffian ducts become the vas deferens, and the cloaca becomes the urethra and rectum.
What occurs during FEMALE fetal development?
Bipotential gonads develop into ovaries, Wolffian ducts degenerate, Müllerian ducts become the uterine tubes and uterus, and the cloaca divides and develops into a vagina, a urethra, and a rectum.
During prenatal development, the fetal circulatory system is integrated with the ___________________ so that the fetus receives both oxygen and nutrients from the _________.
Placenta via the umbilical cord
What happens to the Fetal Circulatory system after birth and the umbilical cord is severed?
The newborn’s circulatory system is reconfigured
When the heart first forms in the embryo, it exists as what?
It exists as two parallel tubes which then fuse together
When does the tube-shaped heart folds and further differentiates into the four chambers present in a mature heart?
As the embryo develops into a fetus
Unlike a mature cardiovascular system, however, the fetal cardiovascular system also includes what?
Circulatory shunts which allow blood flow to bypass immature organs such as the lungs and liver until childbirth
The fetal circulatory system bypasses which organs?
The immature lungs and the liver
What is the Foramen ovale?
It allows blood to move directly from the right atrium to the left atrium, bypassing the lungs.
What is the Ductus arteriosus?
It allows for blood to be shunted from the pulmonary trunk to the aorta, reducing the blood flow to the nonfunctional lungs.
What Fetal Developments occur in weeks 9-12?
- Brain Development: The brain continues to grow.
- Body Elongation: The body begins to lengthen, and ossification continues
- Fetal Movements: Movements become more frequent, and are jerky and uncoordinated.
- Erythrocyte Production: bone marrow begins to take over the production of red blood cells, previously done by the liver
- Liver Function: The liver starts secreting bile.
- Amniotic Fluid Circulation: The fetus swallows amniotic fluid and produces urine.
- Eye Development: The eyes are well-developed, but the eyelids are fused shut.
- Fingers and Toes: Development of nails begins.
By the end of week 12, how long is the fetus?
Approximately 9cm from crown to rump
What Fetal Developments occur in weeks 13-16?
Primarily sensory organ and excretory system development
- Eyes: The eyes move closer together, and blinking motions begin, although the eyelids remain shut.
- Mouth: The fetus exhibits sucking motions with its lips.
- Ears: The ears move upward and lie flatter against the head.
- Hair: The scalp begins growing hair.
- Kidneys: The kidneys are well-formed.
- Meconium: The intestines begin to accumulate meconium, which is made up of swallowed amniotic fluid, cellular debris, mucus, and bile
What Fetal Developments occur in weeks 16-20?
- Fetal Movements: The fetus grows, and limb movements become more powerful, which the pregnant person may begin to feel as “quickening.”
- As space becomes restricted, the fetus typically assumes the “fetal position,” with arms crossed and legs bent at the knees.
Skin protection:
- Vernix Caseosa: Sebaceous glands coat the skin with a waxy substance that protects, moisturizes, and may help with lubrication during childbirth.
- Lanugo: A fine, silky hair covers the skin, which is shed as the fetus continues to grow.
What Fetal Developments occur in weeks 21-30?
- Weight Gain: Rapid weight gain occurs, crucial for temperature regulation after birth.
- Erythrocyte Production: The bone marrow completely takes over the production of red blood cells.
- Nervous System Development: The spinal cord axons begin to myelinate, coating with glial cells to insulate the axons for efficient nervous system function.
- Eye Development: The fetus grow eyelashes and the eyelids are no longer fused; they can open and close.
- Lung Development: The lungs begin to produce surfactant, which reduces surface tension to aid lung expansion after birth.
What can happen if insufficient Surfactant is produced?
Inadequate surfactant production can cause respiratory distress syndrome in premature infants, requiring treatments like surfactant replacement therapy or CPAP.
What happens with MALE fetuses in weeks 21-30?
The testes descend into the scrotum toward the end of this period.
How big is a fetus at the end of week 30?
At 30 weeks, the fetus is about 28 cm (11 inches) from crown to rump.
It has similar body proportions to a full-term newborn, though it remains leaner.
What is Meconium staining?
The first sign of meconium passage usually occurs when the amniotic sac ruptures.
Normal amniotic fluid is clear, but meconium passage (occurring in 5-20% of births) causes it to be greenish or yellowish.
What colour is a newborn’s stool after birth?
The newborn’s first stools consist mostly of meconium, which later transitions to seedy yellow stools (from breast milk) or tan stools (from formula) as the meconium is cleared.
What does the passage of meconium in utero often indicate?
Fetal distress, especially fetal hypoxia (oxygen deprivation).
Why does fetal hypoxia trigger the passage of meconium?
Fetal hypoxia triggers gastrointestinal peristalsis and anal sphincter relaxation, allowing meconium to be released.
Why is the passage of meconium dangerous to the fetus?
The hypoxic stress also induces a gasping reflex, increasing the risk of meconium aspiration into the lungs
What are additional causes of fetal distress?
Maternal drug use (e.g., tobacco or cocaine), maternal hypertension, depletion of amniotic fluid, prolonged labor or difficult birth, placental defects affecting oxygen delivery.
While meconium is sterile, it interferes with the antibiotic properties of the amniotic fluid, making both the newborn and pregnant person more susceptible to infections, which can include…
Infection of fetal membranes, uterine lining inflammation, and neonatal sepsis.
Meconium aspiration during birth can result in complications such as:
Labored breathing, barrel-shaped chest, low Apgar score
How is Meconium Aspiration identified?
Obstetricians can identify it by listening for a coarse rattling sound in the lungs, blood gas tests and chest X-rays can confirm the diagnosis.
Inhaled meconium can lead to…
- Obstruction of airways (causing alveolar collapse)
- Interference with surfactant function (making lung expansion difficult)
- Pulmonary inflammation or hypertension (increasing susceptibility to pulmonary infection)
Vernix caseosa and luango first appear on the fetus at this age:
A)Weeks 0-9
B) Weeks 9-12
C) Weeks 13-16
D) Weeks 16-20
D) Weeks 16-20
How is a due date estimated?
The first day of the last menstrual period (LMP)
How long is an average pregnancy?
It is 284 days (approximately 40.5 weeks) from the LMP.
What does using the LMP assume about conception?
This assumes that conception occurred on day 14 of the menstrual cycle
Where are hormones generated in weeks 7-12?
By the corpus luteum
Where are hormones generated in weeks 12-17?
The placenta is now developed and takes over hormone production
What does Progesterone do during pregnancy?
- Stimulates decidual cells of endometrium that nourish blastocyst before placenta is formed
- Suppresses FSH/LH
- Inhibits uterine contractions until levels drop, allowing labor contractions
- Protects the fetus from preterm birth. It decreases in late pregnancy to allow for labor contractions.
How much do Estrogen levels rise during pregnancy?
Levels climb throughout pregnancy, increasing 30-fold by childbirth
What does the placenta do to androgens secreted by the maternal and fetal adrenal glands?
Converts them to estrogens
What does Estrogen do during pregnancy?
- Suppress FSH and LH production-prevents ovulation.(how hormonal birth control works)
- Induce the growth of fetal tissues (lungs & liver)
- Promote fetal viability by regulating progesterone production and triggering fetal synthesis of cortisol (maturation of the lungs, liver,& endocrine organs-thyroid gland/adrenal gland)
- Stimulate maternal tissue growth, leading to uterine enlargement and mammary duct expansion and branching.
What is the hormone Relaxin?
Secreted by the corpus luteum and placenta, relaxin increases the elasticity of pelvic ligaments and the symphysis pubis, allowing room for the fetus and facilitating childbirth; It also helps dilate the cervix during labor.
What is the hormone hCG?
Produced by the placenta, hCG supports corpus luteum survival and stimulates male fetal gonads to secrete testosterone for male reproductive system development.
What Pituitary hormones are used increased during pregnancy?
Thyrotropin
Prolactin
Adrenocorticotropin hormone (ACTH)
What does Thyrotropin do?
It raises thyroid hormone production, increasing the maternal metabolic rate.
What does Prolactin do?
It enlarges mammary glands for milk production.
What does Adrenocorticotropin hormone (ACTH) do?
It stimulates cortisol secretion for fetal protein synthesis.
Why are Parathyroid hormones increased during pregnancy?
Increased parathyroid levels mobilize calcium from maternal bones for fetal use
What are some of the Urinary and Digestive changes that happen during pregnancy?
- Nausea and vomiting (morning sickness)
- Gastic reflux
- Constipation
- Urinary frequency
What is Morning Sickness?
It is sometimes triggered by an increased sensitivity to odours, are common during the first few weeks to months of pregnancy; typically subsides by week 12.
Why does pregnancy cause morning sickness?
Hormones and decreased intestinal peristalsis may contribute to nausea.
Why might pregnancy cause Gastric Reflux?
It is common later in pregnancy as a result from the upward, constrictive pressure of the growing uterus on the stomach.
Why might pregnancy cause Constipation?
Likely due to decreased peristalsis as pregnancy progresses.
Why does pregnancy increase the need to urinate more frequently?
Due to bladder compression as the uterus grows and the additional urine production as a result of maternal and fetal waste
How much does blood volume increase during pregnancy?
By ~30% (approximately 1–2 liters).
Why does blood volume increase?
It helps to manage the demands of fetal nourishment and fetal waste removal.
As the fetus grows, the uterus compresses underlying pelvic blood vessels, hampering venous return from the legs and pelvic region which can result in what?
Varicose veins & Hemorrhoids
In the 2nd half of pregnancy, respiratory minute volume increases by how much?
By 50%
Why does respiratory minute volume increases during pregnancy?
To compensate for the oxygen demands of the fetus and increased maternal metabolic rate
The growing uterus exerts upward pressure on the diaphragm which…
Decreases the volume of each inspiration and potentially causing shortness of breath (dyspnea)
During the last several weeks of pregnancy dyspnea usually is resolved by what?
It is often resolved by the pelvis becoming more elastic, and the fetus descending lower
It is a process called “Lightening”
Respiratory mucosa swell in response to increased blood flow leading to what?
Nasal congestion and nose bleeds, particularly when the weather is cold and dry.
Counteracted by humidifier use and increased fluid intake
How does the Integumentary system accommodate pregnancy?
The dermis stretches extensively to accommodate the growing uterus, breast tissue, and fat deposits on the thighs and hips.
What causes striae (stretch marks)?
Torn connective tissue beneath the dermis, present as red or purple marks during pregnancy that fade to a silvery white color in the months after childbirth
The Integumentary system increases production of which hormone?
Melanocyte-stimulating hormone
What does the increase of Melanocyte-stimulating hormone do?
It darkens the areolae and creates a line of pigment from the umbilicus to the pubis called the “linea nigra”
What is the Linea nigra?
A line of pigment from the umbilicus to the pubis
Melanin production during pregnancy may also darken or discolor skin on the face to create what?
A chloasma, or “mask of pregnancy.”
What is Parturition?
Childbirth, typically occurs within a week of the due date, often earlier for multiples.
What does Progesterone do leading up to labour?
Progesterone levels are high throughout the early pregnancy to prevent contractions, but levels drop significantly in the 7th month to account for upcoming labour
What do Estrogen levels do leading up to labour?
Levels rise as the pregnancy progresses.
What do Fetal Cortisol levels do leading up to labour?
Rises as the pregnancy progresses and boosts placental secretion of estrogen.
What are Braxton Hicks Contractions?
False labour, initiated by the decreasing levels of progesterone, often relieved with rest or hydration.
What happens to the hormones Estrogen, Progesterone, and hCG throughout the course of a pregnancy?
Estrogen: continues to rise throughout
Progesterone: rises until month 7, then drops
hCG: rises quickly in weeks 6-12, then begins to drop and plateau for the remainder of the pregnancy
What is the “Bloody Show”?
Release of a plug of mucus that has accumulated in the cervical canal, blocking the entrance to the uterus; this happens 1–2 days prior to the onset of true labor, the plug loosens and is expelled with a small amount of blood.
Progesterone levels drop facilitating uterine contractions, uterine contractions result in what?
Oxytocin secretion from the posterior pituitary
What does Oxytocin Secretion do during labour?
It stimulates more labour contractions
As pregnancy progresses more oxytocin receptors causes in an increase of myometrium sensitivity, resulting in what?
Stronger contractions
How is labour a Positive Feedback Loop?
Oxytocin → Stronger contractions → Prostaglandin release (from fetal membranes)
What do Prostaglandins do?
They further enhance contractions
The fetal pituitary also secretions oxytocin to do what?
Boost prostaglandins
How is the fetus positioned before birth?
Head-down (vertex) position stretches myometrium & cervix
What does the Head-down (vertex) position stimulate?
It stimulates contractions
How do you know if you are in True Labour?
You are having regular contractions, increasing in strength & frequency
What causes Labour Pain?
Myometrial hypoxia during contractions
What are the 3 stages of Childbirth?
1) Cervical dilation
2) Expulsion of the newborn
3) Afterbirth
How far does the cervix dilate during labour?
10 cm
How long does it take for the cervix to dilate?
Often 6-12 hours, possibly more
** The longest stage of labour
What also occurs during the Cervical Dilation stage?
Cervical effacement (cervix softens and shortens), and membranes may rupture before, during, or afterwards
What happens during the Expulsion of the Newborn stage?
The stage begins when the fetal head enters the birth canal and ends with birth of the newborn (typically lasts 2 hours)
What happens during the Afterbirth stage?
1) Delivery of the placenta and associated membranes.
2) Continued uterine contractions aid to expulse the placenta.
3) Any retained placenta is removed to reduce the complication of post-partum hemorrhage.
4) Uterus returns to pre-pregnancy size and abdominal organs move to pre-pregnancy spaces
What marks the beginning of the Post-partum period?
The expulsion of the placenta
What is it called when the uterus returns to pre-pregnancy size and abdominal organs move to pre-pregnancy spaces?
Involution
What is Lochia?
Postpartum vaginal discharge (lochia) that is made up of uterine lining cells, erythrocytes, leukocytes, and other debris.
What is lochia rubra (red lochia)?
Lochia that is thick and dark, typically continues for 2–3 days
What is Lochia serosa?
A thinner, pinkish form that continues until about the tenth postpartum day.
What is lochia alba (white lochia)?
A scant, creamy, or watery discharge that may continue for another 1-2 weeks.
How long does the Neonatal period last?
It spans the first to the thirtieth day of life outside of the uterus
How does the Respiratory System work in Utero?
The fetus practices breathing amniotic fluid, but the placenta provides all necessary oxygen; Lungs remain partially collapsed with minimal activity.
What is the trigger for the newborn’s first breath outside the womb?
Labor contractions temporarily reduce oxygen supply, increasing carbon dioxide and causing acidosis, which stimulates the brain’s respiratory center.
When does a newborn’s first breath and lung inflation occur?
Taken within 10 seconds of birth, the first breath inflates the lungs, lowers resistance, opens alveoli, and shifts circulation to independent oxygen exchange.
How does a newborn’s first breath shift their circulatory system?
A newborn’s first breath lowers pulmonary and right heart pressure, initiating circulatory transition.
What causes the Umbilical Cord to close?
Clamping and cutting the umbilical cord collapses its blood vessels
Without intervention, Wharton’s jelly naturally constricts the vessels within 20 minutes due to temperature changes.
What are some of the Circulatory remnants in the newborn?
- Foramen ovale closure
- Ductus arteriosus closure
What happens after the Foramen ovale closure?
Blood briefly reverses through the foramen ovale, pressing its tissue flaps closed.
Over a year, it fuses into the fossa ovalis.
What happens after the Ductus arteriosus closure?
Increased oxygen constricts the ductus arteriosus, which later forms the ligamentum arteriosum, ensuring full pulmonary circulation.
What does the Ductus venosus become?
Ductus venosus becomes the ligamentum venosum beneath the liver.
What does the Umbilical arteries do after birth?
Some proximal sections remain functional, supplying blood to the upper bladder.
The fetal intestine is sterile: why is important that they consume breast milk or formula?
Either one will floods the neonatal gastrointestinal tract with beneficial bacteria that begin to establish the bacterial flora.
The fetal kidneys filter blood and produce urine but are immature so they cannot efficiently do what?
Concentrate urine
Why is it important that infants obtain sufficient fluids from breast milk or formula?
Because they produce only very dilute urine
Why do newborns struggle with temperature regulation?
Newborns lose heat quickly due to high surface area-to-volume ratio, immature muscles, underdeveloped nervous system, and minimal subcutaneous fat.
What is it called that newborns rely on brown fat to generate heat instead of shivering?
Nonshivering Thermogenesis
What are some of brown fat’s unique properties that make it ideal for newborn heat regulation?
It is highly vascularized for fast oxygen delivery and contains special mitochondria that produce more heat instead of ATP.
What does the placenta do in utero to ensure that newborns have brown fat available for warmth after birth?
It inhibits brown fat metabolism
When was Apgar score introduced?
1952
Why were Apgar Scores introduced?
To evaluate wellbeing after birth
What are the 5 criteria of Apgar Scores?
- Appearance (skin color)
- Pulse (heart rate)
- Grimace (reflex)
- Activity (muscle tone)
- Respiration
How are each criteria scored in an Apgar Score?
Each are scored 0, 1, or 2
When are Apgar Scores taken?
1-5 minutes after birth
What is a normal Apgar Score?
8-10
What does an Apgar Score below 7 at 5 minutes indicate?
They may need medical attention
What are the 2 most critical factors of Apgar Scores?
Pulse (heart rate) and Respiration
What do low scores for Pulse and Respirations mean?
They may indicate that the newborn needs resuscitation
What is Lactation?
Milk production and secretion from mammary glands of the postpartum female breast in response to an infant sucking at the nipple.
Why is Lactation good?
1) Provides ideal nutrition and passive immunity for the infant,
2) Encourages mild uterine contractions to return the uterus to its pre-pregnancy size (i.e., involution),
3) Induces a substantial metabolic increase in the postpartum person, consuming the fat reserves stored during pregnancy
What is the composition of normal, non-lactating breasts?
The non-lactating breast consists mostly of adipose and collagenous tissue, with mammary glands being a minor component.
During pregnancy due to estrogen, growth hormone, cortisol, and prolactin, the Laciferous ducts do what?
Expand and branch
Which hormone stimulates the growth of breast alveoli, which contain milk-secreting lactocytes surrounded by contractile myoepithelial cells?
Progesterone
How is milk transported?
Lobules (clusters of alveoli) drain into lactiferous ducts → lactiferous sinuses → nipple pores (4–18 openings).
Which glands in the areola secrete oil to protect the nipple from chapping and cracking during feeding?
The Montgomery glands
What is Prolactin’s role?
Establishes and maintains breast milk supply and mobilizes maternal micronutrients for milk.
Prolactin increases by 10–20x during pregnancy but is inhibited by estrogen and progesterone until birth…when does this inhibition lift?
After placental expulsion, inhibition lifts, and milk production begins.
Prolactin levels do what with each feeding to prepare for the next feeding?
Prolactin levels spike
Infant suckling triggers a neuroendocrine reflex that does what?
Triggers Prolactin to stimulate milk production, and Oxytocin to contract myoepithelial cells and eject milk into ducts.
When does the Let-down reflex occur?
Within 1 minute of suckling.
Doing what maintains high prolactin levels for months?
Frequent milk removal (breastfeeding/pumping)
T or F: Baseline prolactin gradually returns to pre-pregnancy levels even with continued breastfeeding.
True
What are other hormones involved in Lactation?
Growth hormone, cortisol, parathyroid hormone, and insulin help transport maternal nutrients (amino acids, fatty acids, glucose, calcium) into human milk.
Human milk has a laxative effect that aids with what?
Meconium expulsion and bilirubin clearance
What causes excess bilirubin (hyperbilirubinemia)?
Excess bilirubin is caused by immature liver, ineffective feeding, substances in breast milk that slow bilirubin processing, hemolyticcauses
What can happen if bilirubin levels rise too high?
It can cross blood-brain barrier, causing a risk of neurotoxicity (kernicterus).
What are ways to help break down bilirubin in severe cases?
Phototherapy or exchange therapy
