Abstract
BACKGROUND: Exclusive breastfeeding for 6 months is recommended, but breastfeeding safety data is insufficient for several medications. AIM: To determine if mothers treated with chronic medications are less likely to breastfeed. METHODS: For this secondary analysis, 6383 pregnant women in the MotherToBaby cohort recruited from the United States and Canada between 2010 and 2022 were included. Participants treated with antirheumatic medications (ARM), selective serotonin reuptake inhibitors (SSRIs), and asthma medications during pregnancy were divided into two groups based on their medication use: continuers and discontinuers. Breastfeeding initiation, supplementation with commercial milk formula, and discontinuation of breastfeeding before 6 months were compared between those exposed and unexposed to medication use. Adjusted risk and hazard ratios (aRR, aHR) and 95% Confidence Intervals (CI) were calculated with modified Poisson and Cox regressions adjusted for year, parity, socioeconomic status, body mass index, smoking, illicit drug use, race and ethnicity. RESULTS: The sample included 799 (12.5%) continuers and 475 (7.4%) discontinuers of ARM, 293 continuers (4.6%) and 63 (1.0%) discontinuers of SSRIs, and 217 (3.4%) continuers and 97 (1.5%) discontinuers of asthma medications. There were 4,439 (69.6%) participants who were unexposed to the study medications. Both ARM continuers and discontinuers were more likely to not breastfeed (aRRs 95% CI: 3.92 [3.03, 5.07] and 3.08 [2.19, 4.33]), to supplement (aRRs 95% CI: 1.12 [1.01, 1.26] and 1.25 [1.10, 1.43]) and stop breastfeeding before 6 months (aHRs 95% CI: 1.72 [1.29, 2.31] and 1.41 [0.92, 2.15]). SSRI continuers were more likely to supplement (aRR 95% CI: 1.26 [1.08, 1.47]). CONCLUSION: Participants treated with chronic medications, primarily ARMs, were less likely to breastfeed. Targeted lactation support for mothers with chronic illnesses is recommended along with development of breastfeeding safety data for these medications.