Previous research has shown that maternal BMI (body mass index) is associated with reduced breastfeeding. Several studies have shown that increased maternal BMI can affect biological processes such as lactogenesis and that societal factors surrounding increased maternal BMI such as low body confidence can affect breastfeeding. Less is known, however, about any underlying genetic or epigenetic associations between maternal BMI and breastfeeding outcome. We ask to what extent the relationship between maternal BMI and breastfeeding outcome is mediated by changes in the mother’s epigenome, whether any differentially expressed genetic regions are associated with appetite or weight regulation, and how stable these epigenetic associations are across time.