How US mothers store and handle their expressed breast milk

Many mothers express and store their milk to later feed to their infant. Health organizations provide recommendations on expressed milk storage and handling because these practices can affect milk quality and safety. However, little information exists on US mothers' practices.

To describe how US mothers of healthy infants store and handle their expressed milk and to compare their practices with recommendations.

Mothers participating in the Infant Feeding Practices Study II from 2005-2006 who were expressing milk formed the cohort for this analysis (n = 436-1060, depending on infant age). Participants in this longitudinal mail survey were drawn from a consumer opinion panel and answered questions about milk expression around 2, 5, and 7 months postpartum. Data were analyzed cross sectionally using frequency procedures, and the analysis compared mothers who fed expressed milk with and without also feeding formula.

Few mothers stored their milk longer than recommended. Among mothers of the youngest infants in this analysis, 12% heated their milk in a microwave and 17% rinsed bottle nipples with only water before reuse; percentages were similar as infants aged. These practices may pose risks to infant health. Compared with those who fed no formula, mothers who fed both expressed milk and formula were more likely to heat milk in a microwave and, among those with the youngest infants, to rinse bottle nipples with only water between uses.

Consumer education should emphasize safe warming and cleaning practices for feeding expressed milk.