Background: Infant feeding recommendations prioritize exclusive human milk (HM) for the first 4-6 mos. Recent US data show 87% of parent/infant dyads initiate HM, however, some exclusively pump their milk instead of feeding at the breast, i.e., exclusive pumpers. We aimed to describe characteristics of exclusive pumpers and test associations between maternal pre-pregnancy body mass index (BMI) and exclusive pumping (EP). Methods: The Michigan Archive for Research on Child Health (MARCH) is a statewide prospective cohort with prenatal recruitment (n=1,165). Self-reported maternal height and pre-pregnancy weight were obtained early in pregnancy; BMI was calculated. Infant feeding practices were assessed in a 3-month post-partum survey (n=750). The analytic sample included only those who initiated HM feeding (n=651). Feeding groups were defined as exclusive pumpers, breastfeeding only, or mixed feeding - including both pumping and breastfeeding. Multiple logistic regression was used to examine whether pre-pregnancy BMI was associated with EP. Results: Of those who initiated HM, 5% were exclusive pumpers. Maternal characteristics of exclusive pumpers included: 55% White, 58% unmarried, and 77% below bachelor’s degree. BMI categories included 6%, 32%, 10%, and 52% of participants for underweight, normal, overweight, and obese, respectively. Gestational age at delivery ranged from 25-39 wks. The unadjusted model including all BMI categories suggested a weak non-significant association between obesity and a higher chance of EP (OR = 1.8, 95% CI 0.80-4.1) when compared to those using other HM feeding methods. Post hoc subgroup analyses excluding those underweight resulted in significant findings (OR = 3.8, 95% CI 1.07-13.3). Conclusions: Although we did not find a significant association between maternal BMI category overall and EP, odds ratios were strong and understanding characteristics of exclusive pumpers may contribute insights to researchers and healthcare professionals when providing advice to pregnant patients considering alternative feeding methods.
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