Liver problems in pregnancy: distinguishing normal from abnormal hepatic changes.

Abnormal liver tests occur in 1 of 10 pregnancies, though liver function is usually normal during pregnancy. The data suggest that liver metabolic capacity may be reduced in late pregnancy. Hepatic excretory function has been assessed in human pregnancy by both bromosulfophthalein (BSP) and bilirubin tolerance tests. The data suggest that the hepatic excretion of both compounds is impaired in the last half of normal human pregnancy. Thus, the clearance of compounds that are metabolized via the microsomal oxidizing pathway or secreted into bile may be impaired during pregnancy (especially late pregnancy). There is a 20% increase in total body water during pregnancy, and cardiac output increases 30% to 50%. The increment in cardiac output represents shunting of blood to the fetal-placental unit. Serum cholesterol and triglyceride levels begin to rise in the fourth month of pregnancy and peak at term. At term, pregnant women have a 25% to 50% rise in serum cholesterol levels to 265+/-8 mg/dL and a 150% increase in serum triglyceride levels to 180+/-13 mg/dL. Chemical analysis of tissue samples and histologic studies suggest that both cholesterol and triglycerides accumulate in the liver during normal pregnancy. The latter is thought to represent a storage pool of metabolic fuel to sustain the fetus during periods of starvation or inadequate nutrition. It is believed that both the enlarged gallbladder and supersaturation of bile with cholesterol contribute to gallstone formation in pregnant women.