Further investigations regarding the underlying cause and a formal consultation with a hematologist or maternal fetal medicine specialist are reasonable (Class IIa; Level of Evidence B). 9. It is reasonable to treat acute CVT during pregnancy with full-dose LMWH rather than unfractionated heparin (Class IIa; Level of Evidence C). 10. For women with a history of CVT, prophylaxis with LMWH during future pregnancies and the post- partum period is reasonable (Class IIa; Level of Evidence C). Oral Contraceptives On the basis of a US Department of Health and Human Services survey conducted from 2006 to 2008, 10.7 million women aged 15 to 44 years in the United States used the pill form of contraception.214 As alternative forms of hormonal contraception such as the transdermal patch, vaginal ring, and intrauterine devices are increasingly used, the risk of stroke with these formulations also needs to be evaluated. The risk of stroke is very low in the age group of women who use contraception, but the incidence rises steeply from 3.4 per 100000 at ages 15 to 19 years to 64.4 per 100000 in women IS Risk The cumulative risk of stroke in women using OC pills has been summarized in 4 different meta-analyses, with many of the same individual cohort or case-control studies included in each. 