Generally, the mean BPs were most often well below 140/90 mmHg. Importantly, only a very small percent- age ( 2%) of women developed hypertension.234 A systematic review of studies that collected outcomes based on measure- ment of BP before initiation of OCs235 found 2 case-control studies that met criteria for inclusion.220,236 Both studies dem- onstrated a higher OR of IS in women without versus with BP measurement before initiation of OCs, although the CIs A separate case-control study showed no difference in hemorrhagic stroke based on preinitiation BP Taken together, these limited data suggest that OCs appear to marginally increase BP, albeit infrequently leading to hypertension, and that measurement of BP before OC initiation may be an important preventive measure to detect women at risk of stroke. OCs: Summary and Gaps The relative increase in stroke risk with low-dose OCs is small, approximately 1.4 to 2.0 times that of non-OC users.144 On the basis of the longitudinal data from the Danish popu- lation-based study, among 10000 women who use the 20- g dose of desogestrel with ethinyl estradiol for 1 year, 2 women will have arterial thrombosis and 6.8 will have venous throm- The risk of stroke with OC use also appears to be lower than the risk associated with pregnancy ( 3 per 10000 Despite the overall low risk of stroke from hormonal con- traception, certain subgroups of women, particularly those who are older, smoke cigarettes, or have hypertension, dia- betes mellitus, obesity, hypercholesterolemia, or prothrom- botic mutations, may be at higher risk for stroke. Estimates are based primarily on case-control studies and a smaller number of cohort studies primarily from northern European countries, which limits generalizability to other populations. 