The increased risks of stroke and heart attack associated with hormonal contraceptives are significant, but the overall risk remains very low.
Use of hormonal contraceptives is associated with an increased risk of stroke and heart attack, although the overall risk remains quite low, according to the results of a large-scale study
published on June 14, 2012, in the New England Journal of Medicine
The study was based on data from more than 1.6 million nonpregnant Danish women between the ages of 15 and 49 who were followed from 1995 through 2009, yielding more than 14 million person-years of observation. Data on the women’s use of hormonal contraception, clinical end points, and potential confounders was drawn from 4 Danish national registries.
For all participants, there were 3311 strokes (21.4 per 100,000 person-years) and 1725 heart attacks (10.1 per 100,000 person-years). Women who took combined oral contraceptive pills including ethinyl estradiol at a dose of 30 to 40 micrograms were 40% to 120% more likely to have a stroke and 33% to 128% more likely to have a heart attack than nonusers. (For both end points, the risk was lowest for pills that included norgestimate or cyproterone acetate and highest for those that included norethindrone or desogestrel.)
In women who took desogestrel with a 20-microgam dose of ethinyl estradiol, the risk of stroke was increased by 53% and heart attack by 55%. None of the progestin-only contraceptives, including the levonorgestrel-releasing IUD and subcutaneous implants, significantly increased the risk of stroke or heart attack, although the sample sizes were small for some of these groups. In addition, the risk of stroke was increased 149% for those using contraceptive patches, but the number of heart attacks in this group was too low for a reliable risk assessment. It is also possible that the risk of stroke associated with contraceptive patches is inflated because providers perceive them as safer and prescribe them for women at risk of stroke.
Despite the findings of increased risk of stroke and heart attack associated with hormonal contraceptives, these effects pale by comparison with the effects of age. According to the study’s results, the incidence rates of stroke and heart attack were increased 20- and 100-fold, respectively, in the oldest age group (age 45 to 49) compared with the youngest age group (age 15 to 19).