Oral contraceptives are less effective at preventing pregnancy in obese women. Researchers from Oregon State University say they’ve identified a biological mechanism that could explain the failure.

The study, published in the journal Contraception, found that oral contraceptives eventually reach the effective blood concentrations needed in the body to prevent pregnancy in obese women, but it may take twice as long. That would allow for a “window of opportunity” each month. During that time, the contraceptive may not be at a high enough level to prevent a pregnancy.
One problem is that drugs aren’t initially tested for effectiveness on people with a …read more