Progestogens and arterial disease--evidence from the Royal College of General Practitioners' study.

In the course of a large-scale prospective study of the health of oral contraceptive users, the rate of reporting of arterial diseases was examined in two groups of users of pill brands that permitted the effect of the progestogen to be assessed independently of estrogen effect. The rate of reporting was consistently higher with the brands with the higher progestogenic activity. The reports of cerebrovascular diseases showed a significant trend in relation to the dose of norethindrone acetate as well as in relation to total arterial diseases. Total arterial diseases were also reported more frequently in association with brands containing 250 microgram of levonorgestrel than with those containing 150 microgram of this progestogen. The mean serum levels of high-density lipoprotein cholesterol in users of the brands described show a striking inverse relationship to the rate of reporting of arterial diseases and to the progestogenic activity of the pills.