Breast Milk on Ice: How to Build a Freezer Stash Before You Go Back to Work

Work.Pump.Repeat. cover***Update!! From building a freezer stash to talking about your body with the person who signs your paychecks, my new book, Work. Pump. Repeat: The New Mom’s Survival Guide to Breastfeeding and Going Back to Work, is now on sale. You can order now, via:

…and this blog has a new home, at Please join me there!

Now, then…

Once you start thinking about your first day back at work, you’re likely to have some burning questions about how on earth to store up enough milk to leave with your baby’s caregiver. How to build up a stash is the question I get asked most often by new parents.

After you’ve learned how to pump, you have to get on a regular schedule of pumping and saving milk if you want to build up a stash. You have likely heard a lot about the supply and demand aspect of breastfeeding – that supposedly perfect cycle of your body making as much milk as your baby needs. This might make you wonder how you will ever get any additional milk to save for when you go back to work. But it is entirely possible, assuming you have a pretty normal milk supply. (If you have a low supply and/or are already supplementing with formula, you will have to work harder to store up milk, and you are likely looking at your caregiver supplementing during the day. And you are still an awesome parent.)

There are two relatively easy times of day to get that extra milk while you’re still on maternity leave (assuming you got one!):

  1. Pumping immediately after the morning (7 am-ish) feeding
  2. Once your baby is sleeping longer at night, pumping while she is sleeping

Let’s focus on #1, since #2 is less predictable, and you ought to be getting some sleep when you can. Most people’s milk is more abundant in the morning. And pumping in the morning offers the benefit of setting you up for a more milk-productive day, by kicking the day off with some additional demand. Feed and burp your baby, then set her up somewhere comfortable, and sit down to pump. In the first few days or even weeks you might get very little milk when you do this, and you will think I am either a liar or an idiot. But stick with it, and don’t let it freak you out, and you will see the volume go up over time.

The milk you pump can go straight into a freezer bag, or into the fridge until you have enough to fill a freezer bag. Label these bags with the date. If you want to be super organized, freeze them lying flat on their sides to make little flat bricks, then stack the bricks upright in a shoebox in the freezer. Oldest milk (by date) goes in the front, and newest milk in the back. Then you can pull individual bricks out to thaw in the fridge (always thaw inside a ziploc bag, in case of leaks!).

Within a few weeks, you will start to have a nice little supply. (But please, please take note: you do not have to do this additional pumping every single day. Some days you will be tired. Some days your baby will need you, or you’ll just plain not feel like it. Give yourself a break. It’s gonna be ok.)

This now brings us to the “how much?” question.

The obvious answer is that you need enough milk to get your baby through a single workday of feedings. This is based on the premise that you will pump enough on your first day back at work to replenish your at-home supply. But taking into consideration the stress and emotion of the first day back, it’s best to have a bigger stash at home. Let’s call that 3 work days as a goal. If, while still on leave, you are directly nursing for most of your baby’s feedings (rather than bottle feeding formula or expressed milk), you might have no idea how many ounces of milk your baby eats during a typical day. So you can try a whole day of bottle feeding your expressed milk, and arrive at a very clear number of what your baby ate on that day.

But I think the more accurate, and less time-consuming method is to go with pediatricians’ best estimate of what a normal baby eats – on average, 24-26 ounces per day. Every baby is different, and this is an average, but that’s ok; we’re just trying to get to a reasonable number to shoot for. Either way, divide your 24-hour figure by the number of feedings your baby is doing per day (probably between 6 and 8 for a 2-4 month old baby), and figure out how many feedings you will miss by being away at work. There’s your magic number for a single workday.

For example, let’s assume:

  • baby eats 26 ounces per day
  • …and is on 6 feedings in a 24-hour period when you go back to work
  • …that’s 4+ ounces per feeding
  • She eats on a regularish schedule of 7 am, 10 am, 1 pm, 4 pm, 7 pm, and a “dream feed” at 9:30 pm.
  • This means that in a 9 am – 6 pm workday you will miss three feedings
  • …therefore you need to leave her caregiver with 4 (and a bit) ounces times 3 feedings = 13 ounces of milk.
  • Let’s call that 15 ounces just to be safe.
  • So, for a 3-day stash, you need 45 ounces of milk

45 ounces looks daunting on paper, but it is doable if you start early. Even if you were to “bank” only two ounces a day, within about 3 weeks you’d hit your goal. Many people will get much more than a couple of ounces out of that morning pumping session as time goes on. (If you have a short maternity leave or no leave at all, don’t panic. A single day’s worth of milk is great. So is supplementing with formula and building up that stash of milk more slowly. It’s gonna be ok.)

If you have business travel, you will have some additional decision-making to do. Being away from your baby for one or more overnight requires quite a lot of milk in the freezer if you don’t want to supplement. Go back to that 26 ounce average for a 24-hour period. So a three-day business trip would use up something in the neighborhood of 78 ounces of milk. (Of course, you will be pumping on the road, and can bring that milk back with you to replenish – more on flying home with milk here.)

So, are we good? You’re going to take this one day at a time. You’re not going to panic when your first pumping session produces a few measly drops of milk. You’re going to cut yourself a break. And you’re going to be just fine.

Questions? Fire away in the comments, and/or join me on Facebook and ask a question there.


36 thoughts on “Breast Milk on Ice: How to Build a Freezer Stash Before You Go Back to Work

    1. Probably so.
      If you are dead-set on your baby getting only breastmilk when you’re at work, also do this:
      – Start that morning pumping thing now. You can add a pump after any feeding, actually, to see if you can get just a bit more milk.
      – If your baby is sleeping any long stretches at night, set an alarm and get up and pump.
      – If your baby takes an extra-long nap, pump. If he wakes up earlier than you expected, as in soon after you pumped, you can offer him the breast and if he’s not satisfied, offer some of the milk you pumped.

      If you don’t make it to 12-15 ounces saved up for the first day, please don’t beat yourself up over it. Formula is going to be ok, and you can always go back to breastmilk as long as you keep pumping at work and nursing at home. Good luck! Let me know how it goes!


      1. When pumping after feeding in the morning- how long do you suggest pumping for? Also- only pump after 1 feeding per day or multiple? Is it possible to dry out?


      2. I think you’ll figure out how long to pump as you go. Start with 10 minutes and see how that feels. If you’re totally dry after 5 minutes, that’s ok too. It will increase over time.
        You can do it multiple times per day; I just prefer to stick with once because it’s tiring to do all of that and be with your baby and get the rest you need.
        It’s not possible to “dry out” from pumping – your breasts will mostly empty, yes, but they’re always making milk, and by pumping (demand) you are asking them to make more milk (supply).


    1. I think it depends on your leave and how mental health. I’d give yourself a few weeks of rest after delivery, if your time at home allows for it.


  1. I am a new mom (2 and a half week old). We have a few weddings coming up and he will be with my MIL. I want to prepared if I miss a feeding. Can I start building a back up supply or is it too early? Right now, my little one only feeds from one side. If I were to start pumping in the morning, would I just pump from the side he feeds from or from both?


    1. Hi Ami – this is really up to you and how you’re handling the first few weeks postpartum! If you have the mental and physical energy to start pumping once a day, I’d say go for it. You could pump from the other side while he’s feeding, or pump both sides right after he eats – both would work!


  2. Hello,
    I was wondering how long I should wait to pump immediately after breastfeeding. Can I do i right away or should I be waiting 30 minutes or so? Thank you.


    1. Hi Megan
      I’m not a lactation professional, but what I generally hear is that pumping anywhere between right away and 10-15 minutes after nursing is a good time to aim for. You might not get much milk at first, but over time you will.


    1. If it’s possible, it would be good to pump the same # of times your baby is taking a bottle while you’re away. If you can’t produce what your baby is consuming, check out “paced bottle feeding” to make sure s/he isn’t being overfed. If you still can’t keep up, you can add in another pumping session, or consider supplementing with formula or donor milk. Hope that helps!


  3. I’m due in just a couple of weeks and really planning on breastfeeding and pumping. My only worry is I start back to work only around 4-5 weeks after having her depending on when she decides to come! I’ve been reading all the information I can find and was wondering your thoughts/advice on when to start pumping after delivery to start having a good supply to leave with the caregiver while I’m gone.


    1. Nicole,
      If BFing and pumping is a priority for you, you’ll probably have to start pretty early on due to your shorter leave (I’m sorry about that, by the way!). You could start pumping in the hospital, if you really want to get on it – they can probably provide you with a hospital-grade pump that will be pretty powerful. Or you can wait until you get home and get going a few days postpartum. I’d just ask you to look after your mental health – including sleep – as a major priority in this whole picture. The back-to-work situation, with such short leaves, really does not do new moms any favors. If it doesn’t work perfectly for you, it’s not you – it’s the system.


  4. Thank you! You just eased my mind for going back. I hear people saving outrageous amounts like 200oz and felt so overwhelmed. I have the goal you laid out in my freezer now and still have 2 weeks before returning. Thank you!!


    1. I’m not a clinician and would suggest you ask a lactation consultant! also has great advice on stuff like this 🙂


    1. You can experiment, but at first, 1 ounce per bag might be a way to make sure you’re not unnecessarily thawing anything. But if you do thaw, do it in the fridge (inside a tupperware or ziploc) – that way the milk will still be usable for a day or so if you don’t end up using it right away!


  5. Is this the same for someone with twins…. I have twins and have been back to work for a month now. I pump and freeze about 24-30 oz when at work. They take one bottle of formula in the morning then frozen breast milk throughout the day with Nanny and once home I tend to latch them up until bedtime… they get a bottle of formula around 9:00. I’ve been struggling to keep my freezer stash stocked with two little ones 😦 any advice?


    1. My main piece of advice is to realize that you are AMAZING. I am blown away that you are keeping that up!! You should be thrilled with yourself 🙂
      I know it’s stressful, but I always tell people to remember that their own mental health is a super important part of this equation. It sounds like you have a decent balance going, and those little ones are getting some great breastmilk! The only technical advice I’d add is to a) google “hands-on pumping” and b) order the Pumpin Pal flanges. Both can help increase your pumping output. Good luck! You are awesome!


  6. This was so helpful and encouraging! I was totally freaked about having a supply before going back to work. I only get about 5ish ounces per day but it has totally added up and now I have tons of bags of milk in my freezer!


  7. What are your thoughts on combining milk? Can I pump and then combine from a previous session? I was thinking I wanted to fill the storage bags with at least 6 oz. of milk. Or should I maybe be doing 3 oz. each bag, to prevent over thawing milk? My three-month old is a healthy eater lol. I would like to be storing away one bottle per day, at least. Thank you!


    1. I’m not a trained clinician so this is just mom talking to mom. I totally combined milk. I did try to chill the new milk so both sets were cold before I combined, and then I dated it with the oldest milk’s date.

      But 3 oz per bag at the beginning can work, too, so you have more control over it.


      1. Perfect. Thank you for such a quick response!

        Also, how long after pumping do I need to freeze?

        For example… I’m trying to pump a stash for Thanksgiving day, that way I can cook all day and my husband can feed him. Do I have to freeze, or should I just be keeping in fridge?

        I should note that I just started pumping.
        So far, we’ve been exclusively breastfed (Yay!) and fully fed on demand. Thankfully, he took a bottle. We tried today 🙂


  8. What are your thoughts on combining milk? Can I pump and then combine from a previous session? I was thinking I wanted to fill the storage bags with at least 6 oz. of milk. Or should I maybe be doing 3 oz. each bag, to prevent over thawing milk? My three-month old is a healthy eater lol. I would like to be storing away one bottle per day, at least. Thank you!


  9. So just to be clear, do you recommend pumping only at the 7am feeding and then at night? Or also throughout the day? I’ve been confused on how often to pump (trying to increase my supply)


    1. I just think every new parent has to decide what works best with your mental health, and your need for sleep. You could pump round the clock and make a lot of milk and make yourself very unhealthy in the process. It’s a balancing act. If you feel you can handle it, you can add in an extra pumping session during the day – just please take care of yourself.


  10. You are amazing! This is the info I needed! With my son, he was in the NICU for 3 weeks so I pretty much only pumped and breastfeeding never really caught on between us. With my daughter, I was able to breastfeed almost from minute one! I was just unsure how to go about building a supply for when I have to go back to work (ugh)
    Thank you!


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