Results from pooled Phase III studies of ulipristal acetate for emergency contraception

Abstract

Background: Ulipristal acetate (UPA) is a new effective option to prevent unintended pregnancies up to 5 days after unprotected intercourse. We used pooled data from two Phase III studies to refine our understanding of the efficacy of UPA by time from unprotected intercourse and the effects of other factors on pregnancy rates. Study Design: Data from two Phase III studies were pooled to create a larger analysis population. Analyses were performed on the first participation of 2183 women. Results: A total of 41 women became pregnant despite the use of UPA, yielding an overall proportion pregnant of 1.9% (1.3%-2.5%). Proportions of pregnant women were higher among those with further acts of unprotected intercourse in the same cycle and among obese women. These varied from 1.3% (0.9%-2.0%) among nonobese women who had no further acts of unprotected intercourse (n=1704) to 8.3% (0.2%-38.5%) among obese women who had subsequent unprotected intercourse (n=12). Conclusions: UPA is effective and safe in preventing pregnancy after unprotected intercourse. Its effectiveness is lower among women who have subsequent unprotected intercourse and among obese women.