Further analysis of the theoretical effectiveness of the TwoDay method of family planning

This article validates the theoretical effectiveness of a simple approach t o identify the fertile window of the menstrual cycle. The TwoDay method ide ntifies all days in the cycle in which the woman notices cervical secretion s, and the. days immediately following these days, as the period in which t he woman should consider herself fertile. Women who use this method are cou nseled to avoid unprotected intercourse on these days. The theoretical effe ctiveness of the TwoDay method was tested previously by applying the method rules to the menstrual cycles of women from a large data set from the Worl d Health Organization (WHO). For the current study, we administered the sam e analysis to a data set from an Italian Ovulation Method center. These dat a are better suited for the analysis than were the WHO data because they id entify all days with secretions. Results suggest that the method can be hig hly effective in helping women to identify correctly the days on which they should avoid unprotected intercourse if they do not wish to become pregnan t, although some users may identify a few days as fertile that actually are not. (C) 2001 Elsevier Science Inc. All rights reserved.