Storing expressed breast milk: times and tips

If you are a mum who breastfeeds and you need to express milk, whether to go back to work or because you need to give your baby a supplement and you are going to do it with your own milk, in this Happymami post you will find everything you need to know about storing expressed breast milk. We also tell you about the different supplementation techniques you can use to protect your breastfeeding.

How long does breast milk last after expressing?

The length of time breast milk keeps will depend on the temperature at which you store it. It can last from 6-8 hours at room temperature to 6 or 12 months if you use a freezer at less than -19ºC. That is why below we give you a breast milk storage chart that will be very useful to consult whenever you need it.

General recommendations for expressing and storing breast milk.

• Wash your hands before expressing and handling breast milk.
• Use well-washed (hot water and soap) and rinsed containers to store the milk. Or wash them in the dishwasher.
• Use fresh (not frozen) breast milk whenever possible.
• Freeze as soon as possible the breast milk that you are sure will not be used within three days.
• If for any reason you cannot or do not want to freeze the breast milk immediately after expressing it, store it as soon as possible in a fridge, until you use it or freeze it.
• Store breast milk in small amounts (50 – 100 ml) so that you only need to defrost what your baby is going to drink straight away.
• Label the containers of frozen breast milk with the date.
• Defrost the oldest milk first, always.
• Once breast milk has been defrosted, stir it well. Breast milk expressed on different dates can be mixed for the same feed.

Start designing your bottle

Recommendations on defrosting breast milk

Whenever possible, warm the breast milk straight after taking it out of the freezer. Otherwise, keep the cold chain until you can warm it.

What you CAN do

Heat water in a pan and, once it is off the heat, place the container of expressed breast milk inside until it reaches the desired temperature.

Warm it in the microwave (*) and then stir the breast milk well so that its temperature is even.

What you should NOT do

Warm it in a bain-marie (placing the cold or frozen breast milk in a container with cold water and heating the whole thing on the hob). Warm the breast milk directly on the hob. Defrost breast milk in the microwave. Find out more in our newborn care guide.

Types of container for storing breast milk

Containers can be made of either plastic or glass (with a lid that closes securely) and preferably food-grade. A wide opening also makes them easier to clean.

There are also plastic bags for freezing (single bags or ice-cube tray type) which are practical and inexpensive, although they also spill easily, as they are less stable and can be punctured and leak.

It is preferable to store the milk in a double bag. There are also special bags that attach to the breast pump, but they are expensive and single-use.

Changes in the taste of stored milk

Some women have said that their frozen breast milk smells sour or even rancid. This smell is attributed to a change in the structure of the lipids as a result of the freezing and defrosting cycles in fridge-freezers with automatic defrosting.

Although a baby may occasionally refuse it, this is generally not the case and it is not harmful to the baby either.

Freezing breast milk quickly after expressing and warming it immediately after taking it out of the freezer seems to help reduce this problem.

What can you do to stop your expressed breast milk turning sour?

Some mothers have lipase that acts very quickly and within a few hours their milk smells sour. In these cases, what the mother can do is: put her breast milk in a pan and place it on the heat. If you have a thermometer (a kitchen one), wait for the milk to reach 60ºC, take it off the heat, store it in the container it is going to be frozen in, cool it quickly (a little cold water with ice will do) and freeze it. If you do not have a thermometer, you need to watch the heating process: when the milk forms very small bubbles at the sides of the pan, take it off the heat and carry on with the previous procedure.

Expressed breast milk storage chart

Supplementation techniques with breast milk

There are times when it will be necessary to top up your breastfeeding with complementary feeds. Such as when a baby is not gaining enough weight and the paediatrician recommends a supplement. And so that your breastfeeding is not affected, we have different ways of offering the supplement, and so that you can choose the best one for you, we are going to explain them.

What is a supplement and what types are there?

A supplement for an infant is food that the baby receives in addition to the breast and it can be breast milk or formula. Unless your paediatrician says otherwise, you should always try first to supplement with the mother's expressed milk, then with donor milk (if the mother consents) and as a last option with formula milk.

How much supplement should I give my baby?

The amount of supplement to offer your baby will be told to you by the paediatrician. This supplement calculation will depend on the baby's days of life, weight and situation, but you should always make an exact supplementation calculation so as not to interfere with breastfeeds and, as a result, with the mother's milk production. Remember that, if you offer supplementation with formula, it will be important to always try to express the same amount of breast milk from the breast as the amount of formula milk your baby takes. That way your body will understand that it must produce as much milk as your baby takes in. This makes a return to exclusive breastfeeding more likely.

How should you offer the supplement?

The most advisable thing is to supplement the baby after the breastfeed (with whichever supplementation technique you consider most suitable for you) or with a supplemental nursing system while the baby is feeding at the breast.

Supplementation techniques

There are different techniques for giving supplements to a breastfed baby. And when deciding on one method or another, you should prioritise your needs and your baby's. There are many ways and you will find the one that best suits your situation. In addition, to choose the supplementation technique, you should take into account the reason why you decide to supplement, and other factors including:

• The baby's age and their ability to suck effectively or not.
• Whether the method encourages the baby's proper sucking abilities.
• The volume of milk to be given.
• Whether it is intended for short- or long-term use.
• The cost and availability.
• How easy it is to use and clean.
• The preferences of both the mother and the baby. Both should feel comfortable with the chosen method.

Based on these criteria, below we explain the benefits and drawbacks of each method and how to put it into practice, especially in the first weeks of the baby's life.

Start designing your bottle

Feeding with a supplemental nursing system

The supplemental nursing system is a device that allows the baby to receive supplements of expressed breast milk or formula while sucking at the breast. It consists of a milk container (either a bag or a plastic bottle) that the mother hangs around her neck. Through a valve, two tubes come out that must be attached to the mother's breast with adhesive tape and whose end is placed at the tip of the nipple when the baby is going to feed. When the baby latches on and sucks, they get the milk from the system together with the milk from the mother's breast. Sucking helps to stimulate the supply of breast milk and the milk from the system acts as a reward for the baby for sucking correctly.

Different sizes of tube can be used so that the milk flows in a greater or smaller amount as needed. You usually start with the widest, and as the baby's sucking improves, increasingly narrow tubes are used so that they have to work harder. Except when feeding twins, if only one of the two tubes is used, the other must be clamped so that the milk does not spill. After each use, both the container and the tubes must be cleaned thoroughly to maintain hygiene and keep them clear.

• It is especially indicated in relactation processes (the re-establishment of milk production after premature weaning) or when inducing lactation in adopted children.
• It also helps to encourage reluctant babies to suck so that they latch on to the breast, since with the system the food flows faster and in greater quantity than if they only fed at the breast.

Handling the system can be complicated, but with practice mothers become very skilled and it can be highly effective.

Feeding with a spoon

Giving expressed milk with a small spoon is an extremely useful method in the first days of life. If the mother expresses colostrum by hand, it is preferable to collect it straight from the breast with a small spoon and give it to the baby by placing the spoon on their lower lip and encouraging them to lick it. In babies who demand little, who are sleepy, and in all those who do not stimulate the breast effectively, this method helps the mother to build her confidence. It is also a cheap method and available anywhere. It is useful for giving small volumes during the first two or three days of breastfeeding. It is less useful when the baby needs more milk because it can be awkward.

Spoon-container

This is a device similar to a bottle into which the expressed milk is poured, which includes a valve and, instead of a teat, has a container with a contoured rim like a spoon. It is a useful method for babies who have to be separated from their mothers, to give feeds of expressed milk when the mother is not there. It takes large volumes and can be used long term. It is simple to use and can be an acceptable alternative when the person who is going to feed the baby may see other methods as “strange” or more complicated. There are different models available on the market and they are fairly affordable.

Cup or glass feeding

Cup or glass feeding is useful both in premature babies and in full-term newborns. It is a low-cost, comfortable and easy-to-clean method. You can use a container from home and you can also buy specially made cups. It is suitable both for supplementing small amounts and for larger volumes in older babies.

It requires some training to be practical and to stop the milk spilling constantly. The baby should be positioned as upright as possible. The cup is placed on the everted lower lip and tilted so that the milk just touches it. You should not pour the milk into the mouth but rather let the baby bring their tongue forward. Low-weight babies usually carry the milk to their mouth with their tongue, while full-term or older babies suck it.

Finger-syringe or finger-tube feeding

Giving supplements with a syringe involves putting a clean finger into the baby's mouth, resting the pad on their palate and directing the hand downwards as a lever to force the baby to open their mouth. You must check that the lower lip is everted. When the baby starts to suck the finger in the correct position, you begin to feed them, rewarding correct sucks with a little milk. This method is especially useful in babies with latching or ineffective sucking problems, in premature babies, and when mother and baby have to be separated in the first days because of illness in the mother or the baby.

Start designing your bottle

To give the milk supplement, you can in turn use various options:

• A syringe: with your free hand, rest the tip of the syringe on the baby's lower lip, in the gap between the finger and the corner of the mouth, and when they start to suck, slowly pour in the milk, pointing the syringe slightly downwards, so that the baby takes the milk while continuing to suck the finger.
• Giving supplements using only the syringe directly in the mouth, without stimulating sucking with the finger, can encourage the baby to close their mouth and lips and end up developing faulty sucking, which is precisely what you are trying to avoid. For this reason it is preferable to always use the syringe with the finger, not the syringe alone, as it can be counterproductive.
• A syringe connected to a FingerFeeder. The Fingerfeeder is a cone-shaped silicone device that connects to the syringe, so that it can be inserted into the mouth up to the tip of the finger that is touching the palate, to give the milk in the area of the mouth where the baby would suck it as if it were the breast.
• A tube: in this case, the tip of the tube (a nasogastric feeding tube or the tube from a supplemental nursing system will do) must be placed on the pad of the finger when inserting it into the mouth. The tube can be connected to a syringe, to a supplemental nursing system or to a bottle as a homemade system. As the baby sucks, they gradually empty the reservoir used.

The finger-syringe technique needs both hands and can be difficult for one person alone to do. You have to find a way to hold the baby as upright as possible. One option may be to use a cushion or to place them on your legs, resting them raised on a step or a stool.

Bottle feeding

A more comfortable alternative for offering your baby a supplement may be to do it with a bottle. But it is important to use a bottle that is as respectful as possible with your breastfeeding, being as similar as possible to your anatomy, such as the Happymami bottles, a bottle designed to fit each mum and her baby, making it possible to represent your breast in bottle form, preventing confusion in your baby and protecting your breastfeeding.

Conclusion on storing expressed breast milk and supplementation

As we always say, every baby is a world of their own, and the same goes for breast milk: every situation will be different, and you will obviously need to adapt these recommendations to your own situation. If you have any further doubts, at Happymami we have midwives who will be delighted to advise you. Remember that our Happymami bottle is entirely made of silicone and is safe for your baby. A bottle with which you will find the perfect ally to freeze and defrost your breast milk and keep it always perfect.