Combined Hormonal Contraception with Low-Dose Ethinylestradiol is Associated with Modest Reduction of Breast Milk...

Combined hormonal contraception (CHC) is habitually not prescribed to breastfeeding women due to concerns of decreased milk production. This habit is based on inconclusive studies that examined lactation suppression of CHC with high-dose Ethinylestradiol (EE ≥ 30 µg/day). Notably, the effect of oral CHC with current low-dose EE (20 µg/day EE), and of vaginal rings (15 µg/day EE), has not yet been studied. Here, we examine their effect on breastmilk production.

This study included 172 breastfeeding women, and evaluated self-reported breastmilk production, with and without hormonal contraception. Breastfeeding women using CHC with low-dose EE, either orally (N = 20), or vaginally (N = 32), were asked to complete a questionnaire, at two time-points: (1) Before starting CHC, and (2) some 7-10 days after. The questionnaire recorded 12 variables linked with breastfeeding. As a control group, breastfeeding women using progestin-only pills (POP, N = 54) with Desogestrel 75 µg/day, were used. As another control group, breastfeeding women using no hormonal contraception (N = 66) were also asked to complete the same questionnaire.

Vaginal rings, but not oral CHC pills, containing low-dose EE, are associated with a reduction of self-reported expressed breastmilk volume by 20%. Likewise, vaginal rings, but not oral pills, are correlated with impairment of 5 out of 12 breastfeeding variables, namely: (1) breastfeeding interval, (2) self-expressed milk volume, (3) use of milk substitutes, (4) number of night-feedings, and (5) full diapers.

Vaginal rings with low-dose EE (15 µg/day) are associated with a modest, yet significant, decrease in self-expressed breastmilk volume. In contrast, oral CHC pills with low-dose EE (20 µg/day) are not associated with a significant impact on breastmilk production. These findings may have clinical implications for prescribers and patients.