Hormonal contraceptives raise relative risks for thrombotic stroke and myocardial infarction, although the absolute risks are low, according to a New England Journal of Medicine study.
Using Danish national registries, researchers followed 1.6 million women (aged 15 to 49) from 1995 through 2009. Compared with women not using hormonal contraceptives, those currently using combined oral contraceptives containing 30 to 40 μg of ethinyl estradiol had increased relative risks for stroke (RRs ranged from 1.5 to 2.2) and MI (RRs, 1.3 to 2.3). Those using formulations with 20 μg of ethinyl estradiol had somewhat lower risks. Overall, differences in risk according to progestin type were small.
Progestin-only products (e.g., levonorgestrel-releasing IUD and subcutaneous implants) did not raise risks significantly. However, contraceptive patches increased relative risks for stroke (RR, 3.2), as did vaginal rings (RR, 2.5). Data on MI were too sparse to evaluate patch use, and the risk for vaginal rings didn't reach statistical significance.
An editorialist estimates that the number of excess arterial thrombotic events attributable to these contraceptives is about 1 to 2 per 10,000 women per year and that "for an individual woman, the probability of an event is quite small."