Mortality risk associated with the use of oral contraceptives.

Recent studies in Great Britain and the United States have raised serious concern about the safety of oral contraceptives for women aged 40 and over. This article reanalyzes the data published in these studies and shows that a clear understanding of the synergistic effects of smoking and pill use is essential for proper assessment of the safety of oral contraceptives. The present analysis indicates that (1) the use of oral contraceptives, in the absence of smoking, is considerably safer than no fertility control for all ages, including the group aged 40-44; (2) the use of oral contraceptives among smokers aged 40 and over is substantially more hazardous than no fertility control, although there is little difference for light smokers; (3) the use of oral contraceptives among heavy smokers in the group aged 30-39 may be more hazardous than no fertility control; and (4) the use of oral contraceptives among heavy smokers in the group aged 15-29 may be more hazardous than any other method of fertility regulation.