Pregnancy and renal physiology

Pregnancy is characterized by unique physiological changes within the kidney, resulting in a marked increase in renal blood flow and glomerular filtration, which are associated with successful pregnancy outcomes. Early in normal pregnancy there are increases in plasma volume and cardiac output, but a lowered peripheral resistance leads to average blood pressures being lower. A pregnancy-associated respiratory alkalosis occurs. Protein excretion tends to increase slightly in women without kidney disease. Kidney size is increased, and pelvicalyceal system dilatation is noticeable in most women in the third trimester, right greater than left.