This study investigates the prolonged use of privately purchased pasteurized donor milk (PDM) in healthy newborns, which can undermine breastfeeding promotion efforts and waste resources of PDM for more vulnerable newborns. Results reveal that the use of privately purchased PDM was associated with non-medical factors with no direct link to medical limits on exclusive breastfeeding; including cesarean sections, prescription bias, first-time mothers, male newborns, and higher birthweight. These findings can be used to develop strategies to improve breastfeeding practices and conserve PDM for at-risk newborns.