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You probably know that breastfeeding has many benefits for your baby, but it can be difficult to nurse for a year and longer if you’re not always home.

Pumping breast milk ahead of time and storing it means that your baby can get those benefits even if you go back to work or out for an evening. However, storing breast milk isn’t as careless as storing any other food. You need to worry about contamination and spoiling and other issues that could affect your baby.

In this post, we’re walking you through everything you need to know about storing breast milk.

What to Use to Store Breast Milk

There are several ways you can store breastmilk if it’s not being used right away.

Breast Pump Systems

Some breast pumps have a built-in system that you can use if you need to store a few servings.

We recommend the Serenity Electric Breast Pump. Not only is it easy to use with 2-phase extraction technology and an adjustable 10 step suction, but the automated milk storage can also save time. The pump comes with an attachable bottle and stand that you can pump directly into without needing to worry about contamination during transfer. Another bonus is that the Serenity pump is compact and lightweight, so you can easily take it on-the-go. It also qualifies for HSA/FSA coverage.

You can check out the Serenity pump here for $69.95.


Another option is to store breastmilk in sterile bags. When it comes to storage bags, there’s several options that vary by size and design.

  • Self-standing
  • Twist pouches
  • Flat laying bags

All bags are generally freezer safe, leak-proof and BPA-free.

For most storage bags, you can use an adapter to attach it to your breast pump and pump directly into the bag. If you’re storing more than a few bags at a time, you may consider purchasing a storage container to organize and fit more bags in your freezer. Organization systems are available for both flat lying and self-standing bags.

BPA-Free Plastic Bottles and Containers

Some mothers would rather store their milk in bottles and small bowl-like containers. Although most baby products made from plastic are now BPA-free, it’s a good idea to check to make sure.

Containers tend to take up more space and may be more difficult to store, but they have some advantages:

  • Dishwasher safe
  • Environmentally friendly/less waste
  • Can feed baby directly from bottle

Freezer Trays

A lesser known way to store breastmilk is by using a freezer tray. These are basically silicone ice cube trays with a cover. Typically, each cup holds about 1 oz. of milk so you can simply defrost the amount your baby needs. Although it may be tempting to use a regular ice cube tray, remember that breast milk can’t be contaminated, so having a secure cover is essential. If you choose this option, make sure the silicone tray is intact and doesn’t break off on the cube when you defrost it.

How Much Breast Milk Should You Store Ahead of Time?

If you’re a new mother, you may be wondering exactly how much breast milk you should store. The amount you should store in each container or bag depends on how much your baby is drinking on average. From one breast per session, this could be anywhere from 30-135mL, depending on their age and sex (boys tend to drink more). Start with an amount you think is appropriate and adjust the amount of milk in each bag as your baby’s eating habits change. You may also wish to store some breastmilk in smaller amounts in case your baby needs just a bit more.

How much milk you pump and store is up to you and your lifestyle. If you are home all day, you may only want to store it for the occasional time you’re away from your baby. The rest of the time, you may prefer to nurse her. On the other hand, if you’re going back to work or your partner is staying home with the baby instead, you’ll want to pump significantly more milk so formula isn’t needed.

Here’s a general formula for how much breast milk you’ll need to store ahead of time for one week:

How much your baby drinks per serving X how many times your baby nurses while you’re away (figure out average hours between each feeding and how many of those hours you’ll be away).

For example, let’s say your baby drinks 90mL per serving about every 2.5 hours and you’re away at work for 8 hours, 5 days a week.

8 ÷ 2.5 = 3.2

3.2 X 5 = 16 servings

16 X 90mL = 1,440mL or 1.44L per week/288mL per day

That means you’ll need to pump at least 1.44L of milk for the week ahead. If you don’t already have breastmilk stored in your freezer to use, you may want to pump before or after work for the day ahead. In that case, using the example above, you’d want to pump and store at least 3.2 (or 4) servings for the next day (288mL).

How Long to Store Breast Milk After Pumping

How long breast milk lasts depends on how it’s stored. Here’s some general guidelines:

Room Temperature

  • Up to 6 hours
  • Up to 4 hours if stored in a very warm room
  • Try to use milk or store it immediately


  • Up to 5 days
  • Storing in the back of the fridge will keep it the coolest and freshest
  • Try to use milk or store it in freezer within 3 days

Deep Freezer

  • Up to 12 months
  • Try to use milk within 6 months

Note: Preterm babies or sick infants may need to follow different guidelines, so check with your doctor.

Breast Milk Storing Safety

Unlike nursing, storing breast milk has potential problems such as sterilization and spoiling. Here are some tips to keep your baby safe:

Always Label

Many storage bags and containers come with labels, but if not, you’ll need to use your own waterproof labels. You should label the date you expressed so you know how long it’s good for and which bags to use first. If your child goes to daycare, you should also label the bag with their name.

Don’t Fill to the Top

Since breast milk expands when you freeze it, don’t pump your storage bags full. Leave some room so that the milk doesn’t spill out.


When organizing your breastmilk, keep the oldest bags in front to be defrosted first. There are a few safe ways to defrost frozen milk depending on how soon you need it:

  • Running it under warm water
  • Placing it in a bottle warmer
  • Placing it in the fridge

If thawed milk isn’t used within 24 hours, it’s safest to throw it out. While it may be safe for thawed milk to be refrozen, more research needs to be done.

Don’t Use Regular Bags

Bags designed to store breast milk are pre-sterilized and are generally made with extra protection to prevent tears, leaks and contamination. Using a regular household bag could be unsterile and may be too weak to reliably store milk.

The Fresher, The Better

As long as you’re storing your breastmilk according to the guidelines, it’s a safe and healthy way to give your baby the benefits without always having to nurse. With that being said, some evidence suggests that the longer you store your milk in the fridge or freezer, the more Vitamin C it loses. In addition, the milk you express changes over time. That means that milk you pump now may not meet your baby’s nutritional requirements as fully 6 months from now. If your baby won’t drink thawed milk, try shortening the storage time to see if it help.


You can store breast milk in bags, in trays or in plastic containers or bottles. It can last up to 5 days in the fridge or up to 12 months in a deep freezer. How much you store in each bag and pump ahead of time depends on your baby’s feeding habits and your lifestyle. However, you choose to store your milk, remember to label it and follow other precautions to keep it sterile and safe.

Do you have any breast milk storage tips? If you do, tell us in the comments below. If you have any pregnant or new mom friends, be sure to share this post with them, too!

 The Serenity Electric Breast Pump is comfortable, discreet and easy to use. Many reviewers compare it to other pumps, saying it’s uncomplicated and increases milk expression. Get yours for $69.95.

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About Maria Gorobets

Maria Gorobets is the visionary behind Baby Doppler. Maria founded Baby Doppler and is passionate about helping soon-to-be mothers and providing them with the tools to make pregnancy easier. Maria's goal is to make sure that all customers are happy and she strictly lives by that code. She loves to spend time with the family, travel and do extraordinary things in life!

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