Four of seven studies examined in a recent research review comprising 39,531 women suggest that the heaviest women have the highest risk of pregnancy while using the contraceptives.
Yet a closer look at the studies, the review authors say, reveals a more complicated picture.
In one study of oral contraceptive pills, women with a body mass index (BMI) in the overweight range (a BMI of 25 or more) had a higher risk of pregnancy that those in the normal weight range.
In another study of contraceptive skin patches, higher body weight – not higher BMI – was associated with higher risks of pregnancy.
The review appears in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration. (ANI)