Studies examined in a recent 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 of 25+ had a higher risk of pregnancy that those in the normal weight range. In another study of contraceptive skin patches, higher body weight was associated with higher risks of pregnancy.
Many researchers think that metabolic changes associated with obesity — in particular, the amount of body fat — could make hormonal birth control less effective. “However, we know little about how overweight women metabolize hormonal contraceptives,” said Lopez, “since many studies exclude overweight women.”
In the few reports that did include overweight and obese women, some studied overall body weight and others studied BMI, which could affect pregnancy risk in different ways. For instance, BMI studies tend to focus on how body fat might interfere with contraceptive metabolism, while studies of body weight might examine whether a larger woman needs a larger dose of the contraceptive, the authors say.
Women who are obese or overweight also should consider potential health risks from hormonal contraceptives, said Amitasrigowri Murthy, M.D., who directs the reproductive choice program at Bellevue Hospital Center in New York.
Some studies show that estrogen-based contraceptives can increase the risk of heart attack, blood clots, high blood pressure and gallbladder disease in obese women, “who are already at increased risk for these conditions,” Murthy said.
Read the full story at: http://www.newswise.com/articles/view/566330/?sc=dwhn.
Source and thanks to www.newswise.com.
