Effect of progestin compared with combined oral contraceptive pills on lactation: a randomized controlled trial

Abstract

Objective: To estimate the effect of progestin-only compared with combined hormonal contraceptive pills on rates of breastfeeding continuation in postpartum women. Secondary outcomes include infant growth parameters, contraceptive method continuation, and patient satisfaction with breastfeeding and contraceptive method.

Methods: Postpartum breastfeeding women who desired oral contraceptives were randomly assigned to progestin-only and combined hormonal contraceptive pills. At 2 and 8 weeks postpartum, participants completed in-person questionnaires that assessed breastfeeding continuation and contraceptive use. Infant growth parameters including weight, length, and head circumference were assessed at 8 weeks postpartum. Telephone questionnaires assessing breastfeeding, contraceptive continuation, and satisfaction were completed at 3-7 weeks and 4 and 6 months. Breastfeeding continuation was compared between groups using Cox proportional hazards regression. Differences in baseline demographic characteristics and in variables between the two intervention groups were compared using χ tests, Fisher exact test, or two-sample t tests as appropriate.

Results: Breastfeeding continuation rates at 8 weeks (progestin-only 63.5%; combined hormonal 64.1%), contraceptive continuation, and infant growth parameters did not differ between users of progestin-only and combined hormonal contraceptive pills. Infant formula supplementation and maternal perception of inadequate milk supply were associated with decreased rates of breastfeeding in both groups.

Conclusion: Choice of combined hormonal or progestin-only contraceptive pills administered 2 weeks postpartum did not adversely affect breastfeeding continuation.

Clinical trial registration: ClinicalTrials.gov, www.clinicaltrials.gov, NCT01465022.

Figures

Figure 1

Study flow

Figure 2

Cox proportional hazards regression for breastfeeding continuation fit with time-varying covariates of milk concerns and supplementing. N = 64 for combined oral contraceptives and N = 63 for progestin-only pills.

Figure 3

Breastfeeding outcomes at 8 weeks: Continued breastfeeding in combined oral contraceptive (COC, N = 64) vs. progestin-only pill (POP, n=63) groups. Numbers still breastfeeding for weeks 2-8 were 64, 57, 54, 44, 46, 44, 41 for COC, and 63, 54, 48, 49, 49, 43, 40 for POP.

Figure 4

Infant growth: Changes in weight, length and occipitofrontal measurements in infants of women using combined oral contraceptive (COC) versus those using progestin-only pills (POP) between weeks 2 and 8.