Cholesterol balance during pregnancy.

The possibility was examined that the hyperlipidaemia of pregnancy may reflect abnormal cholesterol metabolism, as occurs in some other hyperlipidaemic states. Seven women were studied during the three trimesters of pregnancy and the increase in their plasma lipid concentrations was compared with their sterol balance, measured over 8-day periods in each trimester. Dietary intake of cholesterol was identical during the three study periods. Faecal bile acid excretion peaked during the second trimester and this coincided with the initial rise in plasma triglyceride levels. However, the rise in bile acid output was counter-balanced by a fall in neutral steroid excretion, so that the net cholesterol balance throughout pregnancy was not dissimilar to that reported in healthy non-pregnant women. The hyperlipidaemia of pregnancy is therefore not associated with an increase in cholesterol synthesis, although the altered ratio of bile acids to neutral steroids resembles that reported in other hypertriglycerdaemic states.