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Safety and Wellness > Wellness Resources > Wellness Topics for Infants 0-2 Years

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Whether you're a new mom or a seasoned parenting pro, breastfeeding often comes with its fair share of questions. Here are answers to some common inquiries that mothers - new and veteran - may have.

How do I store my breast milk?

You can freeze and/or refrigerate your pumped (or expressed) breast milk. It's important, though, to store it in clean and sterile bottles with screw caps, hard plastic cups that have tight caps, or nursing bags (pre-sterilized bags meant for breast milk). Also make sure to put a label on each indicating when the milk was pumped. You should not add fresh milk to milk that is already frozen.

How long, exactly, can I store my breast milk?

For healthy full-term infants:

• You can store it at room temperature:
  
  
  • for 4 to 8 hours (at no warmer than 77º Fahrenheit, or 25º Celsius)
• You can store it in the refrigerator:
  
  
  • for up to 2 to 3 days at 32º-39º Fahrenheit (0º-3.9º Celsius)
• You can store it in the freezer (be sure to leave about an inch of space at the top of the container or bottle to allow for expansion of the milk when it freezes):
  
  
  • for up to 2 weeks in a freezer compartment located inside the refrigerator
  • for 3 to 4 months in a freezer that's self-contained and connected on top of or on the side of the refrigerator and is kept at 0º Fahrenheit (-18º Celsius). But be sure to store the milk in the back of the freezer, not in the door)
  • for 6 to 12 months in a deep freezer that's always 4º Fahrenheit (-20º Celsius)

If you thaw frozen milk, you can refrigerate it and use it within 24 hours, but do not refreeze it. And don't save milk from a bottle that your baby already drank out of.

It's also important to note that different resources provide different variations on the amount of time you can store breast milk at room temperature, in the refrigerator, and in the freezer. Talk to your doctor if you have any concerns or questions.

How much of my milk should I store in the freezer?

Although some women may choose to pump large volumes to be frozen, it's a good idea to actually store the breast milk in small portions so as not to waste any. Label the bottles, cups, or bags 2 oz. or 4 oz. (59.1 or 118.2 milliliters), then freeze them.

You could also pour the milk into ice cube trays that have been thoroughly cleaned in hot water, let them freeze until hard, store them in freezer bags, then count up the amount of cubes needed to make a full bottle.

My frozen breast milk changed color. Is this OK?

Breast milk that's been frozen or refrigerated may look a little different from fresh breast milk, but that doesn't mean it's gone bad. It's normal for breast milk to look slightly blue, yellow, or brown when refrigerated or frozen. And it may separate into a creamy looking layer and a lighter, more milk-like layer.

How do I clean bottles and pump parts?

You'll need to boil the nipples, bottles, and washable breast pump supplies (i.e., the breast shields and any other part that touches your breasts or your milk) for 5 to 10 minutes. Check the manufacturer's recommendations for the length of time to boil the parts. (You also can sterilize them with a store-bought countertop or microwaveable sterilizer, but boiling works just as well and costs nothing.) Then you'll need to wash the bottle and pump supplies in hot, soapy water (or run them through the dishwasher) after every use after that. Bottles and nipples can transmit bacteria if they aren't cleaned properly.

Is it safe to microwave my baby's bottles?

The microwave can create dangerous "hot spots" in bottles of formula or breast milk, so you should never microwave them. Instead, you can run the bottle or freezer bag under warm water for a little bit, swirl the bag or bottle around in a bowl of warm water, or thaw the milk in the refrigerator. You can also put your baby's bottles in a pan of warm water (away from the heat of the stove) and then test the temperature by squirting a drop or two on the inside or your wrist before feeding your baby. You also can get bottle warmers for use at home or in the car.

Reviewed by: Larissa Hirsch, MD
Date reviewed: May 2008