- Subjects must have had regular (24 to 32 day) menstrual cycles for the 3-month period preceding entry into the pretreatment observation cycle, excluding postabortal and nonnursing postpartum subjects. Postabortal and nonnursing postpartum subjects must have completed at least 1 regular (24 to 32 day) spontaneous menstrual cycle before entry into the pretreatment observation cycle. The pretreatment observation cycle for all subjects will begin on day 1 of the subsequent spontaneous menses.