Breast milk
The expressed breast milk (EBM) may be stored and later fed to a baby by bottle. It can either be frozen directly in the bottle, or stored in disposable breast milk bags which are more compact when frozen, thus saving space in a freezer. Expressed milk may be kept at room temperature for up to six hours (at 66-72 degrees Fahrenheit, around 20 degrees Celsius), in an insulated cooler with ice packs for up to one day, refrigerated at the back of the refrigerator for up to 5 days (optimal: use or freeze the milk within 3 days), or frozen for 12 months in a deep freeze separate from a refrigerator maintained at a temperature of 0 degrees Fahrenheit or −18 degrees Celsius (optimal: use this milk within 6 months). If using frozen milk, the oldest milk should be thawed and used first. Thawing can be done by placing the frozen milk in the refrigerator the night before intended use, or by placing the milk in a bowl of warm water. Breast milk should never be microwaved as this can produce dangerous hot areas and may also destroy the milk's antibodies. Many experts recommend discarding thawed milk that isn't used within 24 hours. Breast milk changes to meet a baby's needs so that breast milk expressed when a baby is a newborn won't as completely meet the same baby's needs when he or she is a few months older. Also, storage guidelines might differ for preterm, sick or hospitalized infants.