Exposure Concentrations of Infants Breastfed by Women Receiving Biologic Therapies for Inflammatory Bowel Diseases and Effects of Breastfeeding on Infections and Development.

Background & Aims: Exposure to biologic and immunosuppressant agents during breastfeeding is controversial, and there are limited data on safety. We investigated whether biologics are detectable in breast milk from women receiving treatment for inflammatory bowel diseases (IBDs) and whether breastfeeding while receiving treatment is associated with infections or developmental delays.

Methods: We performed a multicenter prospective study of women with IBD and their infants, collecting breast milk samples (n = 72) from patients receiving biologic therapy from October 2013 to November 2015. Drug concentrations were measured in all breast milk samples at several time points within 48 hours of collection and within 168 hours for some samples. Child development was assessed using the Ages and Stages Questionnaire 3, completed by 824 women with IBD (treated or untreated) during pregnancy (620 breastfed, and 204 did not). Data on children's health and development were obtained from mothers and pediatricians, along with information on mothers' medication exposure, IBD history, activity, pregnancy, and postpartum complications. We used chi-squared method or Fisher exact test to determine associations between categorical values and compared differences in continuous outcomes between groups using analysis of variance models. The primary outcome was drug concentration of biologic agents in breast milk (from 72 women) at 1, 12, 24, and 48 hours after dosing and also at 72, 96, 120, and 168 hours for available samples. Secondary outcomes were a range of infant infections and Ages and Stages Questionnaire 3-defined developmental delays among all breastfed infants.

Results: We detected infliximab in breast milk samples from 19 of 29 treated women (maximum, 0.74 μg/mL), adalimumab in 2 of 21 treated women (maximum, 0.71 μg/mL), certolizumab in 3 of 13 treated women (maximum, 0.29 μg/mL), natalizumab in 1 of 2 treated women (maximum, 0.46 μg/mL), and ustekinumab in 4 of 6 treated women (maximum, 1.57 μg/mL); we did not detect golimumab in breast milk from the 1 woman receiving this drug. Rates of infection and developmental milestones at 12 months were similar in breastfed vs non-breastfed infants: any infection, 39% vs 39% in control individuals (P > .99) and milestone score, 87 vs 86 in control individuals (P = .9992). Rates of infection and developmental milestones did not differ among infants whose mothers received treatment with biologics, immunomodulators, or combination therapy compared with unexposed infants (whose mothers received treatment with mesalamines or steroids or no medication).

Conclusions: In a study of women receiving treatment for IBD and their infants, we detected low concentrations of infliximab, adalimumab, certolizumab, natalizumab, and ustekinumab in breast milk samples. We found breastfed infants of mothers on biologics, immunomodulators, or combination therapies to have similar risks of infection and rates of milestone achievement compared with non-breastfed infants or infants unexposed to these drugs. Maternal use of biologic therapy appears compatible with breastfeeding. Clinicaltrials.gov no.: NCT00904878.