Depot Medroxyprogesterone Acetate and Basal Serum Prolactin Levels in Lactating Women

Abstract

In Brief Objective To study the effect of depot medroxyprogesterone acetate on basal serum prolactin levels in lactating women. Methods We compared basal serum prolactin levels in 25 lactating women after depot medroxyprogesterone acetate injection and in 25 lactating women of similar age who were using a copper T380A intrauterine device (control group). This sample size was required in order to have 95% power to detect a significant difference. Basal prolactin levels were evaluated by time-resolved fluoroimmunoassay three times (6 weeks postpartum and 3 and 6 weeks after beginning either contraceptive method). Results At 6 weeks postpartum, before beginning either contraceptive method, the mean prolactin levels in the study and control groups were 991.31 and 948.75 mU/L, respectively (P = .850, 95% confidence interval [CI] −407.57, 492.70). Three weeks later, the mean prolactin levels in the study and control groups were 1156.12 and 860.10 mU/L, respectively (P = .116, 95% CI −76.20, 668.26). At the last follow-up, the mean prolactin levels in the study and control groups were 1127.83 and 710.97 mU/L, respectively (P = .026, 95% CI 51.97, 781.73). There were no significant within-group differences at 6 weeks postpartum before contraception and at 6 weeks after beginning contraception in the study and control groups (P > .05, 95% CI −327.99, 243.02 and −46.76, 522.33, respectively). Conclusion Contraception with depot medroxyprogesterone acetate in lactating women produced higher basal prolactin levels than contraception with copper T380A intrauterine device. Contraception with depot medroxyprogesterone acetate in postpartum lactating women produced higher basal prolactin levels than contraception with a copper T380A intrauterine device.