Results: Overall pregnancy rate was low at 1.2%. Pregnancy rates were also low in women weighing over 80 kg (0.7%) and who were obese
(BMI over 30 kg/m2
) (2.0%). The pooled analyses for pregnancy demonstrated that BMI over 30 kg/m2 decreased efficacy significantly
(odds ratio 8.27, 95% confidence interval = 2.70–25.37) when compared to women in lower BMI categories, mainly influenced by
pregnancies in obese women from one study site. Sensitivity analyses excluding that site showed that obesity was no longer a risk factor;
however, the other studies included too few obese women in the sample to exclude a substantial decrease in efficacy.