A simple risk calculator for contraceptive failure that women can consult when considering spermicide use was the result of a study of 621 women (mean age 29 years) that tested spermicide efficacy. A prediction rule for unintended pregnancy was constructed as well as a scoring system. The study found:
• Overall pregnancy rate was 10.3% over 6 months.
• Age >35 years was protective against pregnancy (OR=0.19) and multi-gravidity was associated with high failure rates (OR=7.24).
• These risk factors along with frequency of unprotected sex were used in a model that maximized sensitivity for pregnancy prediction.
• The model was 97% accurate in predicting women who had a <5% pregnancy risk while using spermicides.
Citation: Schreiber CA, Ratcliffe SJ, Sammel MD, Whittaker PG. A self-assessment efficacy tool for spermicide contraceptive users. [Published online ahead of print October 22, 2015]. Am J Obstet Gynecol. doi: 10.1016/j.ajog.2015.10.018.