How well do male latex condoms work? Pregnancy outcome during one menstrual cycle of use

To evaluate the contraceptive effectiveness of male latex condoms, we assem bled a cohort of 300 women relying on male latex condoms for contraception and followed them prospectively for one menstrual cycle. None of the 234 wo men who completed the study and reported at least one act of intercourse co nceived tone cycle pregnancy rate 0%; 95% CI 0%-2%). Given the pattern of i ntercourse during the cycle and 3 different sets of conception probabilitie s for different days of the cycle, we would have expected between 32 and 36 pregnancies if no condoms had been used. Thus, the prevented fraction due to condom use (effectiveness) is 100% and the lower bounds of the 95% CI ar e between 89% and 90%. For this cohort, male latex condoms were an effectiv e method of contraception. This cost-efficient approach of evaluating contr aceptive effectiveness shows promise for post-marketing studies. (C) 2001 E lsevier Science Inc. All rights reserved.