The effect of progestins in combined oral contraceptives on serum lipids with special reference to high-density lipoproteins.

Fasting serum lipids were measured in a group of 293 women desirous of using oral contraceptives (OCs) and 536 women who had been taking five varieties of OCS for many months before being tested. Parameters studied were serum cholesterol, triglyceride, high-density lipoprotein (HDL), the two main subfractions of HDL, namely, HDL2 and HDL3, and the ratio of HDL2 cholesterol to low-density lipoprotein (LDL) cholesterol. Studies of these five groups of women enabled us to compare the effect of varying amounts of levonorgestrel with norethindrone and to study the effects of estrogen combined with these progestins. The levonorgestrel-containing pills and the progestin-only OC significantly depressed HDL2 cholesterol levels and the ratio of HDL2 to LDL cholesterol.