Women who are overweight or obese have a much higher chance of becoming pregnant because their Pill has failed, researchers have found. Overweight women were 60% more likely to fall pregnant while on the Pill. Obese women were 70% more likely, found a study in Obstetrics and Gynaecology by a team from the Fred Hutchinson Cancer Research Centre in Seattle. It suggested that of 100 women on the Pill, an extra two to four would fall pregnant due to being overweight. The Pill is usually estimated to be over 99% effective. This means that less than one woman in 100 will get pregnant in a year.
