The Lactational Effects of Contraceptive Hormones: an Evaluation (LECHE) Study.

Objective: To estimate the proportion of women for whom use of hormonal contraception was associated with reporting a decreased breast milk supply.

Study Design: The Lactational Effects of Contraceptive Hormones: an Evaluation ("LECHE") Study was an anonymous, internet-based, exploratory, cross-sectional survey of postpartum women using approximately 70 questions. Women were eligible to participate in the survey if they were 18 years or older, had a singleton infant between 3 and 9 months of age, had breastfed this infant for any amount of time and could read English. The survey included questions about breastfeeding, reproductive health, demographic characteristics and the timing of postpartum events.

Results: A total of 3971 participants clicked on the survey. Our final study population included 2922 participants. Overall, 1201 (41%) reported having had milk supply concerns at some point in the first 12 weeks postpartum. The median time from birth until milk supply concerns was 3 weeks (IQR 1-7). Eight hundred fifty-two women (29%) started hormonal contraception in the first 12 weeks postpartum. Fifteen percent (127/852) of women reported new or additional milk supply concerns after starting hormonal contraception. Reported milk supply concerns were higher for women who used hormonal contraception than those who did not (44% vs. 40%; p=.05) Adjusted hazard ratios (HRs) assessing the association between contraceptive use and time to milk supply concerns were not statistically significant (HR 1.18, 95% confidence interval 0.94-1.47 for any type of hormonal contraception).

Conclusions: This study found a slightly increased proportion of reported milk supply concerns among women who started hormonal contraception.

Implications: It is important for caregivers in the postpartum period to recognize the potential for multiple factors, including initiation of hormonal contraception, to affect breastfeeding. Patient-centered counseling can help elicit women's values and preferences regarding breastfeeding and pregnancy prevention.