Maternity (Prenatal, Labor Basics, Postpartum)

Pregnancy induces profound physiologic adaptations across all maternal organ systems to support fetal development and prepare for parturition. Plasma volume expands by approximately 40% to 50% through activation of the renin-angiotensin-aldosterone system and increased sodium retention. Red blood cell mass rises less, producing the dilutional anemia of pregnancy. Cardiac output increases by approximately 30% to 50% through higher heart rate and stroke volume, while systemic vascular resistance falls because of progesterone-mediated smooth-muscle relaxation and the low-resistance uteroplacental circulation. Human chorionic gonadotropin, produced by the syncytiotrophoblast, maintains the corpus luteum early in pregnancy until the placenta assumes progesterone production at approximately 8 to 10 weeks. These changes explain several expected findings: mild dependent ankle edema, increased urinary frequency, physiologic leukorrhea, fatigue, and a modest increase in heart rate. Edema of the face or hands, sudden generalized swelling, severe headache, visual symptoms, or right upper quadrant or epigastric pain is not explained by normal fluid retention and requires assessment for hypertensive disease. At prenatal visits, trend matters more than a single isolated measurement. Blood pressure should be obtained correctly, with hypertension defined...