Weight has no effect on contraceptive efficacy: study

US researchers followed more than 1500 women who were using an oral contraceptive pill, a patch or a vaginal ring for three years, finding 128 cases of contraceptive failure.

The rate of failure was similar across all BMI categories: 8.44% among women with BMI <25, 11% for BMI 25–30 and 8.92% for women with BMI >30.

Those who had a history of a previous unintended pregnancy were nearly three times more likely to experience contraceptive failure but being overweight did not raise the risk, researchers said.

Obstet Gynecol 2013; online Feb 5