Care and Handling While Storing Breastmilk

As a donor, care and handling of breastmilk is sort of glazed over. It seems that the biggest concern is storage time so that it is still good when given to the recipient mom or milk bank. There is a little bit more to it that we need to be aware of.

When donating to a milk bank, there are specific instructions in regards to the containers used and care of pump parts. When I was donating to the milk bank, I was instructed to sterilize my pump parts at least once per day. I was also to collect milk in sterilized containers. They preferred that the milk was donated in the containers they provided since they were rigid. This meant I pumped into bottles that were clean and sterilized, then poured it into their containers.

But, what if you don't fill a whole container in one pumping session? What if you have extra? Can you combine? Are there rules for doing so? These are some of the questions that don't often get answered, but here, I will let you know.

Milk will separate after standing for a while

You can, in fact, combine samples. I'm slightly type A, so for me to have a partial container was not something I'd stand for. It is best for samples to be the same temperature when combined. You should never add fresh milk to frozen milk, and once thawed milk should not be refrozen. Because of this, the best way to combine samples is by saving partial containers in the refrigerator to attain the same temperature before combining. Just remember, if you do this, the fat is likely to have separated so swirl the milk to mix it. Never shake the milk as you can destroy nutrients doing so (see more info here). Once the milk is combined, and your container full, freeze it. You'll always want to freeze the milk as soon as possible to maintain the integrity of the nutrients. Try not to combine several days' worth of samples. It's best if they come from the same day and you don't want to have milk hanging out for several days before it's frozen.

There is also the question of quantity. How much should be frozen together? Should you fill the bags? What about larger storage containers?

When I was pumping for the milk bank, I was shipped 8 oz. containers. I filled these up to the 8 oz. mark. Most containers should not be filled beyond the top mark because the milk will expand as it freezes, but it is usually acceptable to fill it to the top mark. Most commercially available freezer storage bags (use only ones labeled for breastmilk storage) are available in 5-6 oz sizes. Can you fill them to the top mark? Yes. Should you fill them to the top mark? That depends on where your milk is going. With the milk bank, samples are pooled to achieve an ideal calorie, fat, and protein profile, so maximizing space by filling the containers or bags is probably preferred. When donating to individuals, you may want to freeze in smaller quantities. For most babies, it is recommended that that bottles given are no larger than 3-4 oz., smaller for very young babies. You may want to discuss with your recipient what their preferences are. If they are giving smaller bottles, they may want milk stored in smaller quantities so that less is wasted. Once thawed, the milk is on a 24 hour timer in which it must be used. To avoid wasting it, a mom may prefer smaller quantities. Most donors use breastmilk storage bags (unless they are using containers provided by a milk bank) since these do not have to be returned after use.

How should the containers be frozen? Should bags stand or lay flat?

Storing bags standing creates an unusual shape which may
cause storage issues for recipients.

The manner in which the containers are frozen is personal preference, but you may need to discuss this with your recipient. Obviously if you are using containers from a milk bank (or containers for yourself) this isn't an issue, but with bags, they take the shape in which they were frozen, so position may make a difference. I often leave my bags standing. I do this for no other reason than the fact that they stand easily (I've mostly used the Medela Pump 'n' Save bags which stand upright very easily). Other bags many not stand as well. In addition, freezer space may be at a premium for donors or recipients so laying the storage bags flat may be more desirable. If the milk is being shipped, freezing them flat will facilitate easier packing and allow the use of a smaller shipping container.

Remember through the whole process to handle with care. Frozen containers are very susceptible to damage. They may seem solid, but I can tell you from experience, that they will chip and crack if dropped. I have lost far more than I care to admit because the plastic container slipped from my hands. When using bags, it's not uncommon for sharp frozen edges to cause unseen tears or splits in bags. It is often recommend that storage bags be defrosted in a larger clean bowl to avoid spillage and loss. While donors may not need to worry about that, it is important that the frozen bags you are handling don't get banged or scuffed on surfaces to protect them as much as possible from damaging the bag. The more gently they are handled, the more likely they are to remain fully intact.

Lastly, ensure that your samples are received in a timely fashion. It may be a bit of an ego boost to give a large quantity at a single time (believe me, I've been there), but it's more important that it is given in a timely fashion so that it can be used before the expiration date. Don't wait to donate your milk until it is almost expired. The sooner you can get it out of storage, the better.

I hope these tips help! Happy storing!