The influence of medroxyprogesterone on the duration of breast-feeding in mothers in an urban community

Objective: To assess the effect of medroxyprogesterone acetate on lactation when it is given immediately post partum. Design: Prospective cohort study with follow-up through 16 weeks post partum. Setting: Urban teaching hospital in Baltimore, Md. Participants: Consecutive sample (N=95) of mothers who were delivered of healthy, term newborns, had home telephones, received either medroxyprogesterone or non-hormonal contraception at discharge, and were currently breast-feeding their newborns. Main Outcome Measures: Lactation (duration and frequency) and timing of first introduction of formula were measured by weekly telephone interviews. Results: Maternal characteristics included the mean ±SD maternal age (24±5 years), race (90% African American), history of pregnancy (63% multiparous), marital status or relationship (50% married or living with partner), and medical assistance (81% of the recipients received aid). Women who were receiving medroxyprogesterone (n=43) were older (P<.05) and were more likely to be married (P<.05) compared with those who were receiving non-hormonal contraception (n=52). No other factors that were likely to influence lactation were significantly different. Groups did not differ in the baseline-planned duration of lactation. Follow-up data were obtained on 90 women (96%). The groups were comparable in the duration of lactation (medroxyprogesterone: 98%, 74%, 55%, 47%, and 42% were breast-feeding at least once per day at 1,4, 8, 12, and 16 weeks, respectively [ median, 10.14 weeks], vs non-hormonal contraception: 86%, 70%, 47%, 36%, and 30%, respectively [median, 6.57 weeks] [P=. 19]). The percentage of subjects who were exclusively breast-feeding at these times and the timing of formula introduction also did not differ by group. Conclusion: Medroxyprogesterone, when given to mothers in an urban community immediately alter delivery, has no detrimental effect on the duration of lactation, frequency of lactation, and timing of introduction of formula within the first 16 weeks post partum.