Cholesterol
Blood Clot Risk Higher for Women on Birth Control Patch
Thrombotic events, such as stroke, heart attack or blood clots, are rare but serious potential complications of contraceptive use in women. This risk, though small, has been well documented for oral contraceptives (OC). These risks have not been systematically evaluated for a popular, relatively new form of birth control, a transdermal contraceptive system commonly known as the patch.
Alexander Walker, MD, DrPh and colleagues published a large-scale analysis of birth control users comparing the risks of the patch and OC in the February 2007 issue of Obstetrics and Gynecology. For the study, insurance records were used to identify women that used OC or the patch from April 2002 – December 2004, and medical records for over 340,000 women were used to assess the risks of: venous thromboembolism (blood clot), myocardial infarction (heart attack), and stroke associated with the two forms of birth control.
The risk of blood clots was more than 2-fold higher in women using the patch than those women taking oral contraceptives. The risks of heart attack and stroke could not be determined because the incidence of these outcomes was too small (Cole et al. 2007 Ob Gyn 109).
This risk of thromboembolism due to the patch, although double the risk associated with OC, is still small; approximately 4 in 10,000 women using the patch will develop a blood clot according to this study. However, women with other compounding factors, such as anticoagulation or antithrombolytic treatment, major surgery, post-operative complications, or recent pregnancy may want to discuss the risk of blood clots with their doctor before using transdermal contraception.
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