Pregnancy & Childbirth

What anatomical changes occur in pregnancy?

• Uterus: enlarges, fills abdominal cavity, displaces intestines, liver, stomach; pushes diaphragm upward → shortness of breath.

• GI tract: stomach compression → reflux & heartburn.

• Urinary system: bladder compression → frequency, urgency, stress incontinence. Ureters compressed → risk of hydronephrosis.

• Pelvis/vagina: increased vascularity & edema; uterus grows from 60–80 g to ~1000 g.

What physiological changes occur in pregnancy?

• General: weight gain, increased body water, protein/fat/mineral stores, breast enlargement.

• CV system: ↑ blood volume, stroke volume, HR, cardiac output; IVC compression → edema; renal artery compression → hypertension.

• Respiratory: ↑ tidal volume, minute ventilation, O₂ demand; ↓ expiratory reserve & FRC.

• GI: ↑ appetite, ↓ motility.

• Urinary: ↑ GFR, ↑ plasma flow.

• Skin: hyperpigmentation (chloasma, linea nigra, areolae), striae gravidarum, hair loss.

What are the main hormones of pregnancy and their functions?

• hCG: from trophoblast; maintains corpus luteum until placenta takes over. Basis for pregnancy tests.

• Progesterone: relaxes myometrium, maintains endometrium, closes cervix.

• Estrogen: stimulates uterine growth, breast duct growth, ↑ blood flow.

• hPL (human placental lactogen): modulates maternal metabolism, ensures glucose supply for fetus.

• Relaxin: loosens pelvic ligaments, softens cervix.

• Placenta: major source of estrogen & progesterone after ~12 weeks.

How do early pregnancy tests work?

Detect hCG in urine (appears ~8 days after fertilization, detectable at missed period ~14 days post-ovulation). Antibody-based immunoassay produces color change. Confirmatory tests: serum hCG, ultrasound.

What are common uses of fetal ultrasonography?

Confirm pregnancy, assess fetal viability & growth, accurate dating, determine position, detect multiples, and screen for fetal/maternal abnormalities.

What is amniocentesis and its uses?

Withdrawal of amniotic fluid at 14–18 weeks for genetic & biochemical testing. Detects Down syndrome, Tay-Sachs, sickle cell, muscular dystrophies, hemophilia. Also tests lung maturity and survivability. Risk: 0.5% miscarriage.

What is chorionic villus sampling (CVS) and its uses?

Biopsy of chorionic villi at 8–12 weeks for chromosomal & genetic analysis (>50 defects detectable). Detects same disorders as amniocentesis, done earlier. Risk: 1–2% miscarriage.

What are teratogens? Examples?

Agents that cause congenital malformations.

• Chemicals/drugs: alcohol (#1 cause), thalidomide, DES, anticonvulsants, anticoagulants, cocaine.

• Smoking: low birth weight, ↑ mortality.

• Radiation: microcephaly, intellectual disability, skeletal defects.

• Infections: rubella, syphilis, HBV, measles.

What are spontaneous vs induced abortions?

• Spontaneous: miscarriage, natural expulsion before 20 weeks.

• Induced: medical/surgical termination.

  • Mifepristone + misoprostol: <9 weeks, blocks progesterone.

  • Vacuum aspiration: <16 weeks.

  • Dilation & evacuation: 13–16 weeks.

  • Late abortions: up to 24 weeks.

What hormones regulate labor (parturition)?

• Estrogen: ↑ oxytocin receptor density, stimulates prostaglandins (cervical softening).

• Progesterone: declines in effect, removing uterine inhibition.

• Relaxin: softens cervix, pubic symphysis.

• Oxytocin: from posterior pituitary, stimulates powerful uterine contractions (positive feedback).

What are the three stages of labor?

1. Dilation: 6–12 hrs; cervix dilates to 10 cm, contractions, amniotic sac rupture.

2. Expulsion: minutes to hours; from full dilation to delivery of infant.

3. Placental stage: 5–30 mins; placenta expelled, uterine contractions constrict vessels → prevent hemorrhage.

What is breech presentation and how is it managed?

Fetus presents buttocks/legs first (common in prematurity). May cause dystocia. Managed with cesarean section (low transverse uterine incision).

What is an episiotomy? Indications?

Surgical incision of perineum to widen birth canal. Indications: large fetus, breech, fetal distress, forceps delivery. Risks: pain, infection, incontinence.

What are the major risks of prematurity?

Premature = <37 weeks or <2500 g. Risks: poor prenatal care, drug use, age <16 or >35, prior prematurity, fibroids, incompetent cervix. Main problem: Respiratory Distress Syndrome (↓ surfactant). Managed with artificial surfactant + ventilation.

What are neonatal cardiovascular adjustments at birth?

• Umbilical vein → ligamentum teres.

• Umbilical arteries → median umbilical ligaments.

• Ductus venosus → ligamentum venosum.

• Foramen ovale → fossa ovalis.

• Ductus arteriosus → ligamentum arteriosum.

What are neonatal respiratory adjustments at birth?

Lungs inflate at first breath (deep inspiration → cry). Breathing rate ~45/min initially, declines to 12/min. Placental circulation ceases → infant must oxygenate own blood and eliminate CO₂.

What hormones regulate lactation?

• Prolactin: from anterior pituitary, stimulates milk synthesis (inhibited by progesterone during pregnancy).

• Oxytocin: causes milk let-down reflex. Triggered by suckling.

What are the benefits of breastfeeding?

Nutritional (balanced for growth & brain development), immune (IgA, WBCs), ↓ disease risk, enhances growth & neurodevelopment, strengthens maternal bond. Also stimulates oxytocin → helps uterus involute & expel placenta.