Cortisol and the hypercholesterolemia of pregnancy and labor

Lipids and lipoproteins are known to increase substantially during pregnancy and to decrease rapidly after delivery. The factors responsible for the changes have not been identified, however, they could be related to changes in one or more of the endocrine hormones. Since studies relating lipid and lipoprotein changes to cortisol or estradiol concentrations have not been made, we sought to perform such a study. For this study, we measured cholesterol, HDL-C, VLDL/LDL-C, cortisol, and estradiol concentrations from early gestation through delivery in 32 normal pregnant women. During the course of pregnancy, cholesterol increased from 145 to 211 mg/dl (45%); plasma cortisol increased from 8.6 to 17.8 micrograms/dl (107%); and urinary cortisol increased from 0.10 to 0.177 microgram/mg of creatinine (72%). Further significant increases in cholesterol (256 mg/dl, P less than 0.005) and cortisol (77.6 micrograms/dl, P less than 0.001) occurred during labor, and both decreased after delivery. Pooled correlations were calculated and both cholesterol and VLDL/LDL-cholesterol concentrations were found to be related to plasma cortisol as well as to urinary cortisol (P less than 0.001). Plasma estradiol concentrations increased during pregnancy, but not during labor. The results suggest that the increases in cholesterol during pregnancy and labor could be due, in part, to the metabolic and stress-related increases in cortisol. The studies also suggest that both pregnancy and labor and delivery might be useful "natural" models for studying hormonal mechanisms involved in lipid and lipoprotein metabolism.