When the data for all women are combined, the mean risk of pregnancy is estimated to be 4.12% (95% CI 3.77–4.49). This risk of pregnancy is substantially lower than that estimated in studies comparing the effectiveness of the levonorgestrel and Yuzpe regimens.3,4
This is the first report of risk of pregnancy among a population-based cohort of women requesting EC from pharmacists under conditions of routine use. Overall, in the two groups combined, the estimated risk of pregnancy was 4.12%, which is markedly lower than that reported when effectiveness of EC has been estimated in clinical trials.2–5
If the estimates of risk of pregnancy from the present study and related studies are reasonably accurate, the effectiveness of EC among women in the general population may be markedly lower than is currently believed by professionals and advocates for wider EC use. In light of these observations, consideration should be given to revising the information on effectiveness that physicians, pharmacists and other health care professionals provide to women seeking EC.