Postpartum Antibiotic and Probiotic Use and Infant Feeding Patterns in a Low-risk, Term Birth Cohort from British Columbia, Canada

To describe postpartum antibiotic and probiotic exposure to infants in a low risk term cohort. This was a sub-analysis of data from 628 participants enrolled in the Maternal Microbiome Legacy Project (MMLP), a prospective study evaluating the relationship between maternal and infant microbiomes. Data was collected at 10 days and 3 months postpartum. Of 628 participants, 558 (88.9%) and 459 (73.1%) completed questionnaires at the 10-day and 3-month visits, respectively. 92/558 (16.5%) women took antibiotics from delivery to 10 days, 77/459 (16.8%) 10 days to 3 months. Metronidazole (46/92; 50.0%) and Cefazolin (41/92; 44.6%) were most common in the first 10 days, predominantly for suspected/confirmed chorioamnionitis. Cephalexin (27/77; 35.1%) was most common 10 days to 3 months, predominantly for mastitis. 10/628 (1.6%) infants received Ampicillin/Gentamicin secondary to suspected/confirmed chorioamnionitis. From 10 days to 3 months, 18/459 (3.9%) infants received antibiotics. 72/558 (12.9%) women took probiotics from delivery to 10 days, 82/459 (17.9%) 10 days to 3 months. 19/558 (3.4%) gave infants probiotics within the first 10 days, 102/459 (22.2%) 10 days to 3 months. Women most commonly exclusively fed infants breast milk (288/558 (51.6%) delivery to 10 days, 288/459 (62.7%) 10 days to 3 months), with a sizeable proportion breast milk and formula (174/558 (31.2%) delivery to 10 days, 135/459 (29.4%) 10 days to 3 months). Our findings show substantive postpartum antibiotic and probiotic exposure to infants born at term from low-risk pregnancies. These important potential confounders will be correlated with our infant gut microbiome data.