Studies have shown that freshly expressed breastmilk can be stored
at room temperature, (79 degrees F), for up to six hours, (Hamosh 1996) or
at 66 to 72 degrees for up to 10 hours (Barger and Bull 1987). I usually recommend leaving breastmilk at room temperature for no more than four hours. Breastmilk varies from mother to mother, and room temperature is often a subjective measure that varies over time.