The U.S. Centers for Disease Control and Prevention offers these suggestions:

• Wash your hands before you pump or handle breast milk.
• Make sure you store the milk in containers that are clean and have a tight seal. Examples may include bottles with a screw cap, plastic cups with lids that fit tightly, or bags that are designed for use with milk and bottles.
• Label the container of breast milk with the date, so you know which containers to use first. Include baby's name if it will be taken to your child's care provider.
• Never add fresh breast milk to frozen milk that is already stored.
• Never save or re-feed milk from a partially consumed bottle.

-- Diana Kohnle