An approach to the analysis of menstrual patterns in the critical evaluation of contraceptives.

An approach to a standardized analysis of menstrual bleeding patterns is presented. The method utilizes a prospective bleeding record and characterizes the menstrual pattern of a woman according to bleeding and nonbleeding events without imposing definitions of cycle or intermenstrual bleeding. Further, the analysis is done within a time reference period similar to life-table analysis, with the experience of each woman having equal value. The method is thus applicable to the study of menstrual patterns of both normal, untreated women, and women on experimental contraceptive regimens in which expected bleeding patterns are disrupted. The methodology is aided by computer programs to process the data and by the use of standard statistical packages for comparison of output data of different groups.