Natural family planning: postpartum period.

The length of the postpartum anovulatory period was studied in 200 mothers by means of endometrial biopsy, basal body temperature, vaginal cytology, and cervical mucus. The occurrence of the first ovulation and the first bleeding after childbirth are analyzed in relation to the type of nursing. The characteristics of 408 postpartum menstrual cycles are studied, by means of the same methodology. The shortest anovulatory period for nonnursing mothers was 36 days; for partial nursing mothers, 40 days; and for full nursing mothers, 70 days. The first postpartum bleeding appeared to be preceded by ovulation in 41% of the full nursing mothers, 75% of partial nursing mothers, and 91% of nonnursing mothers. Postpartum cycles were significantly longer and showed a luteal phase significantly shorter than control cycles, especially when the mother was fully nursing.