To date, there is little in the literature that describes any relationship between newborn circumcision, its timing, and breastfeeding outcomes. We sought to determine if the timing of circumcision in term, healthy newborns affects exclusive breastfeeding rates during the first 6 months of life.

One hundred and forty-eight maternal-infant dyads were enrolled in a randomized, multicenter, clinical trial between June 2016 and July 2019. Study participants included parent-infant dyads who desired both circumcision and breastfeeding. Newborns were randomized into 3 groups for circumcision: “early,” circumcised within 24 hours of delivery; “intermediate,” circumcised between 24 to 72 hours of age; and “late,” circumcised between 1 and 3 weeks of age. The primary outcome was exclusive breastfeeding duration, assessed at discharge, 2 weeks, and 2, 4, and 6 months.

Baseline characteristics between groups were similar. Exclusive breastfeeding decreased more rapidly over 6 months in the intermediate group (by 74%, 89% to 23%), as compared to the early (by 34%, 81% to 53%) or late (by 50%, 88% to 44%) groups (P = .04). Exclusive breastfeeding was less common in the intermediate group (circumcision between 24 and 72 hours), as compared to the early and late circumcision groups, at each measured time point beyond 2 weeks of age.

Circumcision before 24 hours of age may be advantageous with respect to increased exclusive breastfeeding throughout the first 6 months of life. Deferral of circumcision beyond the immediate newborn period was not superior to performing the procedure within the first 24 hours.