This cohort comprised 49259 Swedish women who were followed up from 1991 to 1992 In the 285 cases of incident stroke that included ischemic, hemorrhagic, and unknown types, there was no significant association between OC use, duration, or type of OC. Reproductive factors, such as age at first birth, duration of breastfeeding, age at menarche, mean menstrual cycle days at age 30 years, and parity, were not associated with stroke after adjustment for cigarette smoking, hypertension, diabe- tes mellitus, alcohol, body mass index (BMI), education, and The second study estimated rates of IS only (excluding hemorrhagic stroke and transient ischemic attacks [TIAs]) in women aged 15 to 49 years and the RRs associated with use of various doses and formulations of hormonal contracep- tion in Denmark.144 In this population-based cohort of 1.6 million women, the crude incidence of IS in contraceptive users was 21.4 per 100000 person-years. The adjusted RR for ethinyl estradiol doses from 30 to 40 g ranged from RR for the 20- g dose ranged from 0.88 (0.22 3.53) to 1.53 (1.26 1.87). Progestin-only formulations were not associated with IS. The transdermal patch was associated with a nonsig- nificant increased risk in a small number of cases (RR, 3.15; 95% CI, 0.79 12.60), whereas the vaginal ring was associ- ated with a 2.49-fold increased risk (95% CI, 1.41 4.41). In addition, duration of use did not change the risk estimates.144 Although this study followed a very large number of women, it is limited because risk factors and stroke cases were based Bushnell et al Guidelines for Prevention of Stroke in Women 1559 on administrative data. 