In a retrospective review of 302 hospital charts, 38 percent of newborns whose mothers planned to exclusively breastfeed received formula before hospital discharge. Those breastfeeding infants who did not receive formula were significantly younger at first breastfeeding than infants who received formula. Significantly more infants born by cesarean (51 percent) received supplementation than those born vaginally (31 percent). Birth between 9 p.m. and 10 a.m. and a hospital stay for more than 24 hours increased odds of supplementation. Nurses can explore barriers to exclusive breastfeeding unique to their hospitals to develop strategies that facilitate breastfeeding support and decrease formula supplementation.