Multicenter study of endocrine function and plasma lipids and lipoproteins in women using oral contraceptives containing desogestrel progestin. UK Desogen Study Group.

We assessed endocrine function and plasma lipid and lipoprotein concentrations in 112 women given a monophasic oral contraceptive containing 30 micrograms ethinyl estradiol and 150 micrograms desogestrel. These women were participating in a larger trial of cycle control and safety. Plasma concentrations of gonadotrophins, estradiol, and progesterone fell over the 18 months of this study, consistent with suppression of the hypothalamic-pituitary-ovarian (HPO) axis. There was no consistent effect on plasma prolactin concentrations. Concentrations of total triiodothyronine, thyroxine, and cortisol increased, tracking increases in their binding proteins. Within 6 months, plasma total cholesterol concentrations had increased by 12% (p < 0.001) with no effect on those of low density lipoproteins. Concentrations of triglycerides and high-density lipoprotein cholesterol increased by 79% and 14%, respectively (both p < 0.001). Monophasic ethinyl estradiol/desogestrel effectively suppressed the HPO axis. Other endocrine changes were typical of oral contraceptives containing ethinyl estradiol. The increase in triglyceride concentrations is not considered to increase cardiovascular risk, whereas the increase in high-density lipoproteins may be protective.