The use-effectiveness of natural methods of family planning in lactation is evaluated by comparing the incidence of unplanned pregnancies in a group of nursing mothers practising these methods with the incidences reported previously in surveys of breastfeeding women using no contraception. The complexity of the physiological processes involved in the resumption of ovulation after term pregnancy is discussed in relation to NFP and the problems encountered by its users in the context of normal family life. The serum prolactin and gonadotrophin levels are correlated with the postpartum interval and nursing status of the participants and discussed in relation to NFP after childbirth.
PIP: This study assessed the use-effectiveness of natural family planning (NFP) during lactation. Of the 251 postpartum women in the study, 208 (83%) were lactating and 43 (17%) were nonlactating. All were using NFP methods. The resumption of fertility was significantly delayed in breastfeeding women. In these women, the mean time to 1st ovulation was 193 days compared with 95 days in nonbreastfeeding mothers; similarly, the mean time to 1st menstruation in these 2 groups was 179 days and 103 days, respectively. The mean time from weaning to 1st ovulation in lactating women was 60 days. Ovulation preceded 1st menstruation in 107 (51%) nursing mothers and 26 (60%) nonlactating mothers. Serum prolactin concentrations were closely associated with nursing status and related to the duration of breastfeeding. Unplanned pregnancies occurred in 34 (16%) breastfeeding women and 2 (5%) nonnursing mothers in the 1-year postpartum study period. 7 of these pregnancies in breastfeeding women occurred during lactational amenorrhea; 1 pregnancy occurred in a nonnursing woman during postpartum amenorrhea. The incidence of unplanned pregnancy at 12 months (11.1%) was double that at 9 months after delivery (5.8%). These results indicate a lack of use-effectiveness of NFP after pregnancy. It is noted that the resumption of cyclical ovarian activity is complex and variable, and the hormonal fluctuations encountered in the postpartum period do not appear conducive to the methodical use of NFP.