Effect of skim milk supplementation of the maternal diet on lactational amenorrhea, maternal prolactin, and lactational behavior.

Effect of skim milk supplementation of the maternal diet on lactational amenorrhea was studied in 30 pairs of healthy lactating women matched for parity, body mass index, and previous experience of lactational amenorrhea. Supplementation of the maternal diet had no significant effect on the time of resumption of regular menstruation or ovulation, maternal prolactin concentrations, breast-feeding pattern, maternal body mass index, or infant weight. However, the supplemented group breast-fed nearly exclusively (supplemental feeds were introduced but did not exceed 20% of total feeds) for a significantly longer duration (P < 0.05) than did the control group. Previous experience of lactational amenorrhea was significantly positively correlated with the time of resumption of menstruation in the supplemented (P < 0.01) and control (P < 0.05) groups when frequency of breast-feeding, maternal body mass index, and supplementary feeds to the infant were controlled for. Thus, maternal nutritional supplementation does not appear to affect the contraceptive benefit of lactation when the frequency of breast-feeding is not compromised but apparently lengthens the duration of nearly full breast-feeding.