Perinatal and Fetal Development - Vocabulary Flashcards
SEXUAL RESPONSE CYCLE (as per Page 14)
EXCITEMENT/PLATEAU PHASE (implied by initial descriptions):
Vagina swells from increased blood flow; vaginal walls darken to purple; clitoris becomes highly sensitive and retracts under the clitoral hood
To avoid direct stimulation from the penis, the man's testicles are withdrawn up into the scrotum; the man's testicles swell; his scrotum tightens and he begins producing a lubricating liquid
3. ORGASM PHASE (CLIMAX)
General characteristics: climax of the sexual response cycle; shortest phase, generally lasting only a few seconds; involuntary muscle contractions
BP, heart rate, and breathing at their highest; rapid intake of oxygen; feet muscles spasm; sudden forceful release of sexual tension
WOMEN: vaginal muscles contract; uterus undergoes rhythmic contractions
MEN: rhythmic contractions at the base of the penis lead to ejaculation; a rash or sex flush may appear over the body
4. RESOLUTION PHASE
General characteristics: body slowly returns to normal functioning; swollen/erect parts return to previous size/color; sense of well-being; often fatigue
WOMEN/MEN: some may rapidly return to orgasm with additional stimulation and may experience multiple orgasms
REFRACTORY PERIOD
Recovery time after orgasm during which orgasm cannot be reached again
Duration varies among men and changes with age
PERINATAL PERIOD (Overview from Page 14-16)
COMMENCEMENT AND ENDS
Commences at 22 weeks or 154 days of gestation
Ends at 7 completed days after birth
THREE TRANSITION PERIODS
PRENATAL: during pregnancy/before birth
INTRAPARTAL: labor/delivery
POSTPARTUM: period after delivery
PRENATAL CARE (CARE OF THE FETUS)
FETAL FORMATION AND FERTILIZATION (CONCEPTION)
Sperm lives for ext{lives for }72 ext{ hrs} (roughly 48 hrs before ovulation and 24 hrs after); average travel time ~46 ext{ hours}
Sperm must be in the genital tract 4-6 ext{ hours} before fertilizing an egg
Hyaluronidase enzyme dissolves hyaluronic acid that holds ovum together; enables fertilization
Ova survive 24-48 ext{ hrs} only
HYALURONIDASE: enzyme that dissolves hyaluronic acid covering the ovum
FERTILIZATION PROCESSES (Factors Affected)
Equal maturation of sperm and ovum
Two key processes: ext{sperm capacitation} and ext{acrosomal reaction}
Sperm capacitation: sperm hypermobility, plasma membrane breakdown exposing acrosomal membrane, enabling binding to zona pellucida
Acrosomal reaction: hyaluronidase released from acrosomal cap allows penetration of corona radiata and zona pellucida
Upon fertilization, sperm contacts vitelline (zona pellucida) membrane; cortical granule release prevents multiple sperm penetration
ZYGOTE TO EMBRYO (Chromosomal):
When fertilization occurs, the male pronucleus unites with the female pronucleus, restoring chromosome number to 46
The zygote forms a new combination of genetic material (unique individual)
Ovum and sperm each contribute 23 chromosomes; total 46
22 pairs are autosomes; the last pair are sex chromosomes (determine sex)
Ovum contributes X; sperm contributes X → FEMALE; Ovum contributes X; sperm contributes Y → MALE
EMBRYONIC DEVELOPMENT (Embryogenesis) & IMPLANTATION (Pages 15-16)
EMBRYONIC DEVELOPMENT OVERVIEW
Fertilization occurs in the fallopian tubes (uterine tube)
After fertilization, cleavage divisions progress: 2 cells → 4 → 8 → …
Morula: when cell number reaches 16
Blastula (blastocyst): hollow ball of cells with a fluid-filled cavity; differentiation starts
Blastocyst differentiation includes an inner cell mass and an outer trophoblast
Trophoblast attaches to the endometrium; inner cell mass differentiates to form embryo proper
Embryogenesis requires nutrition; implantation is essential for nourishment
DIFFERENTIATION AND PLACENTA
Differentiation: cells become specialized
Blastocyst contains differentiated cells; once embedded, nourishment is established via the placenta
IMPLANTATION (nidation)
Occurs ~8-10 days after fertilization at the fundal portion of the uterus (upper 1/3 of uterus; can be anterior or posterior)
Ectopic pregnancy occurs when implantation is outside the uterus (e.g., fallopian tube); dangerous if rupture occurs
Blastocyst buries itself entirely in endometrium; placentation begins
Amniotic sac forms around the embryo with amniotic fluid; membranes include Amnion and Chorion
Langerhans layer of placenta protects against some viruses in early pregnancy
Trophoblast forms chorionic villi that attach to endometrium; placenta forms from chorionic villi and decidua basalis
Low-lying implantation (placenta previa) can obstruct the cervix and complicate delivery
Placenta functions: oxygen/nutrient transfer, waste removal, gas exchange, endocrine secretion
PLACENTA: STRUCTURE AND FUNCTIONS
Placenta: organ that develops in the uterus; provides oxygen and nutrients to the fetus; removes fetal wastes
Umbilical cord arises from placenta and attaches to the fetus; AVA (artery-vein-artery) arrangement: 2 arteries, 1 vein
Normal cord: 3 vessels (2 arteries, 1 vein)
Wharton’s jelly surrounds the vessels to prevent compression
Nuchal cord: cord wrapping around the neck is common and may occur during pregnancy, labor, or delivery
Placental sides: Maternal side = Duncan (dirty, ragged, beefy appearance); Fetal side = Schultz (shiny, smooth); cotyledons observed at delivery; missing cotyledons may indicate placental fragments requiring attention
PLACENTAL HORMONES (and their roles)
HCG (Human Chorionic Gonadotropin): secreted as early as 8-10 days after fertilization; detected in serum at implantation; present in urine and blood after first missed period up to 1-2 weeks postpartum; suppresses maternal immune rejection of the placenta; typical quantity ~ N = 4 imes 10^5 ext{ IU}/24 ext{ h}
HCG and hydatidiform mole: hydatidiform mole is a trophoblastic disease with trophoblast proliferation that can mimic pregnancy; not all high HCG indicates pregnancy
Progesterone: maintains pregnancy and prevents uterine contractions
Estrogen: mammary development and uterine development
HCS/Human Placental Lactogen (also called human placental lactogen, or HPL): secreted by the placenta beginning in the third week after ovulation; resembles growth hormone; acts as insulin antagonist (glucose-sparing effect); prepares breast for lactation
AMNIOTIC FLUID (Page 18-19)
Clear, straw-colored fluid surrounding the fetus; originates from fetus and mother; fetal urine contributes after week 10; pH around 7.2 (slightly alkaline)
Typical volume: 800 ext{ mL} - 1200 ext{ mL}
Abnormal volumes:
Oligohydramnios: < 500 ext{ mL}; suggests kidney issues
Polyhydramnios: > 2000 ext{ mL}; may indicate esophageal atresia or excessive amniotic fluid
Meconium-stained amniotic fluid: green discoloration; indicates fetal stool expelled intrauterine, especially later gestation
Golden amniotic fluid: suggests hemolytic disease and bilirubin overload
AMNIOTIC FLUID FUNCTIONS
Shock absorber; protects fetus; allows symmetrical growth and movement
Medium for excretion; specimen for diagnostic exams; fetal temperature regulation; maintains amniotic pressure and placental perfusion during labor
UMBILICAL CORD (Page 20)
Conduit between fetus and placenta; length ≈ 55 ext{ cm} at term; contains 1 ext{ vein} + 2 ext{ arteries}
Blood vessels enclosed by Wharton’s jelly
Function: transport oxygen and nutrients to fetus; remove wastes back to placenta
AVA arrangement: arteries (2) carry deoxygenated blood; vein (1) carries oxygenated blood to fetus
Nuchal cord: can wrap around fetal neck
FETAL CIRCULATION AND TRANSITIONS (Pages 20-22)
FETAL CIRCULATION SHUNTS (to bypass immature lungs and liver)
FORAMEN OVALE: right atrium to left atrium shunt; bypasses lungs; normal in fetus, normally closes after birth
DUCTUS ARTERIOSUS: connects pulmonary artery to aorta; blood can bypass lungs via the ductus arteriosus
DUCTUS VENOSUS: shunt from placenta via the umbilical vein to the inferior vena cava; allows highly oxygenated blood to bypass the liver; most blood bypasses liver; remainder perfuses liver
FETAL CIRCULATION (Video summary) – Key flow
Blood from placenta via umbilical vein → ductus venosus → inferior vena cava → right atrium
From right atrium, some goes to right ventricle to pulmonary artery; most crosses via foramen ovale to left atrium → left ventricle → aorta → body
Blood that goes to right ventricle mainly goes to the pulmonary artery and then via ductus arteriosus to the aorta
Lungs are fluid-filled; high pulmonary vascular resistance directs more blood through the ductus arteriosus
Pressure in right atrium is higher than left, promoting foramen ovale flow
Only ~8% of right ventricular output goes to lungs; most goes through ductus arteriosus to the body
Umbilical arteries: carry blood from the body back to the placenta for oxygen/nutrients exchange
TRANSITION TO POSTNATAL CIRCULATION AFTER BIRTH
At birth, cord clamped; placenta removed; systemic vascular resistance increases; lungs inflate; alveolar vessels dilate with oxygen
Pulmonary pressures decrease; at ~6-8 weeks postnatally, pulmonary vascular resistance normalizes
Foramen ovale closes due to increased left atrial pressure; functional closure within weeks; permanent closure by about 3 months; Patent Foramen Ovale (PFO) may persist in 15-25% of adults
Ductus arteriosus: typically closes within 4-10 days after birth; functional closure occurs earlier with breathing at birth
Ductus venosus: closes within 3-7 days; remnant becomes ligamentum venosum; umbilical vessels become ligaments
RESPIRATORY SYSTEM (Endoderm) & NEURAL DEVELOPMENT (Pages 23-24)
RESPIRATORY SYSTEM
Not functional until birth; develops from a single tube that separates into esophagus and trachea by the 4th week of gestation
Lecithin/Sphingomyelin (L/S) ratio used to assess fetal lung maturity; surfactant production begins around 24 ext{ weeks}; prevents alveolar collapse at expiration
Betamethasone (steroid) can be given to the mother to accelerate surfactant synthesis if preterm birth is anticipated
If preterm birth occurs, neonatal care may include endotracheal intubation and artificial surfactants
NERVOUS SYSTEM
Develops from ectoderm; neural plate forms by ~3 weeks AOG; neural tube forms CNS (brain and spinal cord); neural crest forms PNS
Brain development occurs in utero; full maturity occurs after birth; rapid brain growth continues into early childhood
Folic acid deficiency linked to neural tube defects (e.g., spina bifida); prenatal vitamins include folic acid to reduce risk
DIGESTIVE & REPRODUCTIVE SYSTEMS (Pages 24-25)
DIGESTIVE SYSTEM
Develops from endoderm
Sterile gut at birth; newborn gut lacks normal flora; vitamin K synthesis depends on intestinal bacteria; low vitamin K in newborns
Atresia and stenosis are common congenital GI defects; esophageal atresia may occur from failure of trachea and esophagus to separate properly
Omphalocele: abdominal contents herniate through umbilical ring due to abdominal wall closure failure
Meconium: first stool of the newborn; composed of intestinal cells, lanugo, mucus, amniotic fluid, bile; viscous and dark olive green; important nursing task to document passage
Fetal liver remains active; immature at birth; risk of hypoglycemia and hyperbilirubinemia in first 24 hours; mother’s substances cross the placenta
REPRODUCTIVE SYSTEM
Develops from mesoderm
Gonads develop around ~6 weeks AOG; sex determined at conception by sperm carrying X or Y
Testosterone influences male duct development; absence leads to female organs
Testes form in abdomen and descend into scrotum around weeks 34-38; preterm infants may have undescended testes; follow-up necessary for descent
URINARY SYSTEM
Kidneys not essential for fetal life; placenta handles waste clearance
Fetal urine forms by ~12 weeks; excreted into amniotic fluid by ~16 weeks; average fetal urine ~500 ext{ mL/day}
Oligohydramnios may indicate poor fetal urine production
INTEGUMENTARY SYSTEM
Fetal skin translucent until subcutaneous fat deposition (~36 weeks)
Lanugo: fine downy hair; appears around 16 weeks; diminishing by ~36 weeks
Vernix caseosa: creamy coating for lubrication and protection; forms by ~20 weeks; shed before birth
IMMUNE, ENDOCRINE, ENERGETIC SYSTEMS (Pages 25-26)
IMMUNE SYSTEM
IgG crosses placental barrier starting about week 20; provides passive immunity; peaks at birth; declines over ~8 months as infant builds its own stores
IgA and IgM are produced after infections and indicate fetal exposure; they do not cross the placenta
ENDOCRINE SYSTEM
Endocrine functions begin with neural system development
Fetal pancreas produces insulin; insulin does not cross placenta
Thyroid/parathyroid important for metabolism and calcium balance
Fetal/adrenal glands supply precursors for placental estrogen synthesis
MUSCULOSKELETAL SYSTEM
Early fetal life: cartilage templates; ossification begins around 12 ext{ weeks}; most bones ossify later; some bones (carpals, tarsals, sternum) ossify near birth
Fetal movement detectable by ultrasound by ~11 weeks; maternal perception of movement (quickening) typically by 16-20 weeks; more common earlier with multigravida
FETAL MILESTONES, MONTH-BY-MONTH DEVELOPMENT & TRIMESTERS (Pages 25-27)
MONTH-BY-MONTH OVERVIEW
MONTH 1: amniotic sac forms; placenta develops; primitive face; heart tube beating ~65 bpm by end of 4th week; length ~ 1/4 inch
MONTH 2: facial features form; ears, limbs; neural tube closed; heart beat detectable around week 6; embryo becomes fetus after week 8
MONTH 3: limbs fully formed; nails forming; external ears formed; reproductive organs develop but sex unclear on ultrasound; end of month: ~4 inches long, ~1 oz
MONTH 4: heartbeat audible via Doppler; digits defined; hair and nails form; body grows; end of month: ~6 inches, ~4 oz; sex discernible on ultrasound
MONTH 5: quickening occurs; lanugo covers body; vernix caseosa forms; end of month: ~10 inches, 1/2 to 1 lb
MONTH 6: skin reddish and veiny; prints visible; eyes open; end of month: ~12 inches, ~2 lbs; viability improves if born prematurely (≈ 23 weeks with care)
MONTH 7: hearing develops; fetus changes position; amniotic fluid reduces; end of month: ~14 inches, 2-4 lbs
MONTH 8: lungs developing; brain rapid development; ~18 inches, ~5 lbs
MONTH 9: lungs mature; reflexes coordinated; ready for birth; ~18-20 inches, ~7 lbs
TRIMESTERS
1ST TRIMESTER: rapid organogenesis; high teratogen vulnerability
2ND TRIMESTER: most comfortable period; fetus grows and matures
3RD TRIMESTER: rapid fetal growth; fat deposition; iron and calcium demand
ESTIMATED DATE OF BIRTH (EDB)
Healthcare responsibility to determine EDB
Naegele’s Rule (LMP-based):
EDB = ext{LMP} - 3 ext{ months} + 7 ext{ days} + 1 ext{ year}
Month-specific adjustments (Miss Batayola’s discussion):
If LMP in January–March: ext{EDB} = ext{LMP} + 9 ext{ months} + 7 ext{ days}
If LMP in April–December: ext{EDB} = ext{LMP} - 3 ext{ months} + 7 ext{ days} + 1 ext{ year}
FETAL GROWTH ASSESSMENT HISTORY TAKING
Nutritional intake and maternal lifestyle impact fetal growth
Assess personal habits: smoking, drugs, alcohol; exercise
Ask about accidents or intimate partner abuse to assess trauma risk
FUNDUS AND FUNDAL HEIGHT ASSESSMENTS
FUNDUS: palpate from xiphoid process downward to locate uterus contraction site during labor
TWO METHODS TO ESTIMATE AGE OF GESTATION (AOG) FROM FUNDAL HEIGHT
BARTHOLOMEW’S RULE OF FOURS: fundal height landmarks at 12, 16, 20 weeks, and full term
MCDONALD’S RULE: fundal height in cm roughly equals weeks of gestation between 20–31 weeks; limitations in later gestation due to fetal weight gain
JOHNSON’S RULE (FH cm): n × 155 = FW (grams) where n depends on engagement status
NOTE: Ensure the patient voids prior to measurement; keep hands warm; avoid causing contractions
ASSESSMENT OF FETAL WELL-BEING (Pages 28-30) 1) FETAL HEART RATE (FHR)
Normal range: roughly 110–160 bpm after 28 weeks; measured via Doppler, fetoscope or stethoscope
2) FETAL MOVEMENT (QUICKENING)10 kicks per hour (roughly 2 per 10 minutes) is typical
SADOVSKY METHOD: lie on left side after meals; count movements for 1 hour; normal ~10–12 movements per hour; fewer than 10 requires rebroadcast monitoring; instruct to call clinician if movements are consistently fewer than normal
3) RHYTHM STRIP TESTING (FHR variability)Baseline FHR: average rate per minute; variability reflects autonomic regulation and oxygenation
Categories: Absent, Minimal, Moderate (6–25 BPM), Marked (>25 BPM)
Accelerations: increases in FHR with fetal movement
Decelerations: decreases associated with stress or contractions
Positioning to left lateral side reduces vena cava compression; avoid complete supine position
4) CARDIFF COUNT-TO-TEN MOVEMENT METHODRecord time to reach 10 fetal movements; typical window ~60 minutes; variability due to sleep/wake cycles; reassure; trigger after meals or other activity to stimulate movement
5) NONSTRESS TESTING (NST)Measures FHR response to fetal movements with maternal pressing call button
Reactive NST: two accelerations of at least 15 bpm lasting ≥15 seconds within 20 minutes (per standard pacing); non-reactive NST may indicate insufficient oxygen or sleep; duration typically 10–20 minutes; home monitoring possible
Interpretations: Reactive vs Non-Reactive; additional movements or low variability considered
6) CONTRACTION STRESS TESTING (CST / OCT)Uses oxytocin to induce contractions or nipple stimulation to release endogenous oxytocin
Negative (normal): no decelerations with 3 contractions
Positive (abnormal): decelerations with contractions
CardioTopograph can monitor FHR and contractions simultaneously
7) VIBROACOUSTIC STIMULATIONApplies ~80 dB at 80 Hz to wake baby for monitoring during stress or NST
8) ULTRASONOGRAPHYUsed early to confirm pregnancy and monitor placenta, amniotic fluid, fetal growth, structural anomalies
Assess fetal sex, presentation, maturity via biparietal diameter, etc.
Pre-procedure guidance: reassure patient; full bladder may help reflect better ultrasound signals; position with slight left tilt to prevent vena cava compression; warm gel
Doppler velocimetry provides blood flow data
9) BIOPHYSICAL PROFILE (BPP)Combines NST with ultrasound to assess fetal well-being across five components: fetal breathing movements, fetal movements, fetal tone, amniotic fluid volume, and FHRNST reactivity
Scoring: normal 8–10, suspicious 6, or 4 or less indicates risk; each criterion scores 0 or 2
Amniotic fluid index (AFI) and oligohydramnios/polyhydramnios evaluation included
10) MODIFIED BIOPHYSICAL PROFILE (MBPP)MBPP triggers BPP if abnormal findings are observed; includes AFI and NST
11) PLACENTAL GRADINGPlacenta grading via ultrasound: Grade 0 to Grade 3 corresponding to gestational age and maturity
12) MATERNAL SERUM SCREENINGMaternal serum AFP (alpha-fetoprotein) screening for neural tube defects; elevated AFP suggests open neural tube defects or abdominal wall defects; low AFP may indicate chromosomal anomalies
Additional markers may include acetylcholinesterase, bilirubin, etc.
13) AMNIOCENTESISInvasive procedure with ultrasound guidance to aspirate amniotic fluid for genetic testing and fetal well-being assessment; performed 18 weeks onward; risks include trauma, infection, preterm labor; mother instructed to void; positioning in left lateral tilt; sample analysis includes AFP, acetylcholinesterase, bilirubin, genetic analysis, and L/S ratio, among others
14) PERCUTANEOUS UMBILICAL BLOOD SAMPLING (Cordocentesis)Performed in 2nd–3rd trimester via ultrasound guidance to sample fetal blood for testing
15) FETOSCOPYVisual inspection of fetus via fetoscope, typically 16–17 weeks onward; used to assess fetal well-being
TERATOGENS, PATERNAL EXPOSURE & FDA PREGNANCY CATEGORIES (Pages 31-32)
TERATOGENS
Teratogen: any factor (chemical or physical) that adversely affects the fertilized ovum, embryo, or fetus; common manifestations include restricted growth or fetal death, malformations, or carcinogenesis
PATERNAL EXPOSURE
Substances affecting sperm quality, size, shape, or function may increase fetal risk
COMMON TERATOGENS
Smoking, recreational drugs, prescription drugs, alcohol, caffeine, radiation, environmental chemicals, occupational hazards, infectious agents (TORCH: Toxoplasmosis, Other, Rubella, Cytomegalovirus, Herpes)
FDA PREGNANCY CATEGORIES
A: Controlled studies show no risk in first trimester
B: Animal studies show no risk or insufficient human data
C: Animal studies show risk; benefits may outweigh risks
D: Evidence of risk to human fetus; benefits may outweigh risks in serious conditions
X: Risks outweigh benefits; should be avoided
PRENATAL ASSESSMENT & OBSTETRIC SCORING (Pages 31-32)
PRENATAL ASSESSMENT
History: collect obstetric history; assess gravidity, parity, prior outcomes
Consider risk factors such as maternal health, nutrition, lifestyle, injuries, abuse
OBSTETRICAL HISTORY CLASSIFICATIONS (GP & GTPAL)
GRAVIDITY (G): total number of pregnancies (including current) regardless of outcome; multiple gestations counted as one
PARITY (P): number of births after 20 weeks gestation (alive or stillborn)
TERM: births at 37–42 weeks
PRETERM: births 20–36 weeks
ABORTION/ABORTUS: pregnancy losses before 20 weeks
LIVING: number of living children (including multiples counted individually)
2-POINT-SYSTEM (GP)
Example: G3 P0 indicates currently pregnant with three prior pregnancies, no prior births beyond viability
G3 P1 indicates pregnant with three pregnancies and one prior birth
G1 P0 indicates one prior pregnancy with current pregnancy and no births above viability
4-POINT SYSTEM (GTPAL)
Gravidity, Term, Parity, Abortion, Living
Twins/triplets counted as one pregnancy
ADDITIONAL NOTES
The transcript emphasizes detailed clinical techniques, exact measurements, and procedural steps for fetal assessment and obstetric scoring. It also highlights common obstetric complications (e.g., placenta previa, placental abruption risk factors) and the importance of patient education and safety (e.g., left lateral tilt during procedures, empty bladder guidelines).
Formulas and Key Numbers (LaTeX-ready):
Fetal dose/measurements and hormones
N=400{,}000\ \text{IU}/24\ \text{h} (HCG production/amount)
EDB = ext{LMP} - 3\ \text{months} + 7\ \text{days} + 1\ \text{year} (Naegele's Rule)
If LMP in Jan–Mar: EDB = ext{LMP} + 9\ \text{months} + 7\ \text{days}
ext{L/S ratio} = 2:1 (lung maturity marker)
Amniotic fluid volumes: <500\ \text{mL} (oligohydramnios); >2000\ \text{mL} (polyhydramnios)
Fetal movement targets: roughly 10\ \text{kicks/hour} (Sadovsky method)
NST: accelerations of at least +15\ \text{bpm} for +15\ \text{sec}
Birth weight estimates: FW = n \times 155\text{ g} where n depends on engagement status
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