Maternal physiology during pregnancy

Pregnancy involves a number changes in anatomy, physiology, and biochemistry, which can challenge maternal reserves
A. Cardiovascular system
-the heart rotates on its long axis in a left-upward displacement.
-the heart size increases by about 12%
-blood volume: 50% elevation in plasma volume, 30% increase in red cell mass.
-cardiac output increases approximately 40%, stroke volume increase 25-30%
-blood pressure: systemic arterial pressure declines slightly reaching a nadir at 24-28 weeks of gestation. Pulse pressure widens because the fall is greater for diastolic than for systolic pressures. Venous pressure increase in the lower extremities which can cause edema and varicosities.
-heart murmurs and rhythm can be detected in 90% or more gravidas. Its can be heard at the left sternal edge.
-peripheral vascular resistance decreases by enhancing local vasodilators(nitric oxide, prostacyclin, possibly adenosine)
-blood flow distribution: uterine blood flow can be as high as 800ml/min, breast 200ml/min.
B. Pulmonary system
-capillary dilatation leads to engorgement of the nasopharynx, larynx, trachea, and bronchi.
-diaphragma is elevated by as much as 4cm.
-dead space volume increase because of relaxation of the musculature of conducting airways.
C. Renal system
-the renal calyces and pelves are dilated
-ureters are dilated above the brim of the bony pelvis, with more prominent effects on the right.
-GFR increases 25%, renal clearence 50%
-sometimes glucosuria, protein loss <300mg
-urinary frequency increase
-bladder capacity up to 1,5L
D. Gastointestinal system
-salivation increases
-gums become hypertrophic and hyperemic
-esophageal peristalsis is decreased
-gastrin increases
-intestine motility decrease
-emptying gallbladder is slowed