Pumping & Storing Your Breast Milk

breast milk storage bags in freezer

You’ve been breastfeeding for a month or so, and now it’s time to start stockpiling your milk to start bottle training your baby before you return to work. Or, you may not be returning to work, but you may want to incorporate Daddy into one of the daily feedings. How in the world do you begin?

You have chosen the perfect pump for your situation, now how do you keep this liquid gold from spoiling once you’ve expressed it?

These storage guidelines will help you make your milk last longer for you and baby:

Of course, you can pump the milk and feed it to your baby when freshly expressed. This method will keep the integrity of the milk at its best- almost as if the baby had latched on to you for that feeding. However, there will be times that you’ll need to plan ahead and store your milk.

Your milk can last approximately this long for these storage circumstances:

  • When freshly pumped, it can stay at room temperature up to 4 hours.
  • In a cooler bag with ice packs, your milk will last approximately 24 hours.
  • In the refrigerator, your milk will last approximately 1 week.
  • In your freezer, your milk lasts approximately 4 months.
  • In a stand alone, deep freezer, your milk can last up to 1 year.

When storing in the fridge or freezer, make sure that your milk is not close to the door where it will thaw each time the unit is opened. Glass bottles keep the integrity of the milk best, but BPA free plastic bottles also work. Many mothers like the ease of storage in breast milk storage bags. These are a great option as well.

When thawing frozen milk, it is best to move the frozen milk into the refrigerator for a day as a step-down process. However, if you don’t have time to do this, thawing straight from the freezer is fine, too. Never microwave the milk! Microwaving creates heat patches in the milk that can burn a baby’s mouth. It also kills many of the properties that you are trying to preserve by expressing your milk in the first place. You can run hot water from the tap or heat some water and place it in a mug. Then, place the bag or bottle of your expressed milk into the cup of water. You can swish the bottle around in the warm water so that the ice crystals break apart more quickly. Test the milk on the inside of your wrist. If it is room temperature or body temperature, then it is ready to serve to your baby. If it is too warm, wait a few minutes until the milk cools off or fill the mug with cool water to cool the bottle down.

Never reheat used milk. Once the bottle of milk has touched your baby’s mouth, bacteria crosses into the milk. The enzymes in your baby’s saliva breaks the milk down and oral bacteria begins to multiply in the bottle as it sits stagnant. Therefore, even if you have 2 ounces left over in a bottle, after 1 hour, the milk should be discarded. This is why it is a good idea to store your expressed milk in containers of different volume portions, so as not to waste any of your precious expressed breast milk.

You can however, reheat unused, yet thawed milk within 24 hours. For example, you anticipate a bottle-feeding for dad, but he is late coming home from work. The bottle was already prepared, but was never given to the baby. You can store that milk in the refrigerator again and reheat it within a period of 24 hours without the milk spoiling.

There is one anomaly I do want to address about expressed breast milk. A low percentage of women will have a high lipase content in their breast milk. Lipase is the enzyme that breaks down the lipids (fats) in the breast milk. When breast milk is expressed and frozen, the moms with a high lipase content will experience a higher break down of the milk. Thus, the milk will smell soapy, silvery, and/or spoiled- like when cow’s milk spoils when it is past its expiration date. There is hope for storage of this type of milk!

First test your milk. Express some milk and store it for a week or two in the freezer. Once thawed, smell or taste it. If it is spoiled or soapy smelling/tasting, you need to pasteurize your milk in order to be able to store it in the freezer. There’s nothing worse than finding out you have a high lipase content and your milk has soured when you’ve already pumped 30 or 40 baggies full of your milk.

To pasteurize it, you must scald your milk. How do you do this? Place your expressed milk in a saucepan on the stove on medium heat. Allow the milk to heat to the point that it begins to let off a few bubbles here and there, but not completely to the boiling point. Remove the pan from the heat and let your milk cool. The best containers to store your milk in for this situation are glass storage bottles. Now your milk will stay true in the freezer without spoiling.

To transport your milk to the babysitter or whoever will be taking care of your baby, a lunch cooler with ice packs works perfectly. Oftentimes, when purchasing a pump, a cooler and ice pack is provided as part of the breast pump ensemble. You’ll also need a cooler and ice packs to bring home your milk when pumping at work.

Remember to pump every 2 ½ to 3 hours for at least 10-20 minutes on each breast when at work. Hopefully you’ll have a clean, private place where you can pump without being bothered, preferably not in a restroom. Many companies have workplace lactation programs. Please inquire what your company’s lactation policies are from your human resources department or from your boss prior to your maternity leave. Most mothers utilize their coffee breaks and lunches to do their pumping.

You are now ready to successfully provide your breast milk for your baby when you are apart from him/her. Expressing your milk will allow you to continue to give your baby the best nutrition and the gift of health even while you are away!

Written for Nursing Bra Express by Veronica Tingzon, IBCLC