How Much Breast Milk to Store Before Going Back to Work

Going back to work while still giving your baby breast milk takes a little planning: a small stash of frozen milk, started a few weeks before you go back, then a routine for pumping at work. No official guideline says how much breast milk to store before returning to work, and a small stash is often enough. Here's what the CDC, the AAP and the Office on Women's Health say, and what federal law guarantees at work.

When should you start building a breast milk stash?

The CDC suggests starting to pump a few weeks before you return to work: it gives you time to practice pumping and helps your baby get used to a bottle. The AAP's HealthyChildren.org suggests starting your freezer supply 3 to 4 weeks before going back, and pumping right after the first morning feeding, when many parents have more milk than their baby drinks.

For the bottle itself, the Office on Women's Health suggests waiting at least a month after birth before offering one. If your baby has trouble taking a bottle at first, the CDC suggests having another adult give it.

How much breast milk should you store?

No official source gives an amount, in ounces or in bottles. The CDC talks about "a few extra ounces" in the freezer, for your baby's bottles during the first day or week of daycare; the AAP about enough bottles to get through the first few days of pumping at work.

That's because, once you're back, the milk you pump at work one day becomes your baby's bottles the next day. The freezer stash is a cushion for the first days and for the days when pumping gives less, not a supply for weeks.

To estimate what your baby will drink while you're apart, here are the official benchmarks. As the CDC puts it, every baby is different: how much and how often a baby feeds depends on their needs.

Benchmark	Source
Breastfed babies between 1 and 6 months take an average of 2 to 3 oz per feeding, an amount that doesn't increase much as they grow	Office on Women's Health
Most breastfed babies take about 1 oz per feeding in the first few weeks, slowly increasing to roughly 4.5 oz at a year	AAP (HealthyChildren.org)
Babies in daycare typically take 2 to 4 oz of breast milk per feeding	Academy of Breastfeeding Medicine
A breastfed baby feeds about 8 to 12 times in 24 hours	CDC

The Office on Women's Health also notes that some babies drink less during the day while apart from their nursing parent, then nurse more often at night ("reverse cycling"): you may then need to pump less milk for the daytime.

You may see a rule of "1 oz per hour away from your baby" online: none of the official sources listed here mention it.

How should you freeze your stash?

Small portions of 2 to 4 oz, or the amount of one feeding, so you only thaw what will be drunk (CDC).
Freeze right away any milk you won't use within 4 days (CDC), at 0°F or colder, in the back of the freezer.
Leave about one inch at the top of each bag or container, because milk expands as it freezes.
Label each container with the date it was pumped, and your baby's name if it goes to daycare.
Use the oldest first: frozen milk is best within about 6 months, and up to 12 months is acceptable (CDC).

All the other storage times (fridge, thawed, warmed) are in our breast milk storage guidelines.

Pumping at work: what does the law say?

Since December 29, 2022, the PUMP for Nursing Mothers Act has extended the pumping protections of the Fair Labor Standards Act (FLSA) to nearly all employees the FLSA covers, including salaried employees who are exempt from overtime. According to the Department of Labor:

for 1 year after your baby's birth, you have the right to reasonable break time to pump each time you need to. No number or length of breaks is set, and your employer can't deny you a needed break or require a doctor's note;
you have the right to a place other than a bathroom, even a private one, shielded from view and free from intrusion from coworkers and the public, with at least a place to sit and a flat surface for your pump other than the floor;
your employer doesn't have to provide a fridge, but must let you bring a pump and a cooler, and give you a place to keep them while you work;
pump breaks don't have to be paid, unless you aren't completely relieved from duty during the break, you use breaks that are already paid, or a state or local law requires it. A salaried exempt employee's pay can't be reduced for pump breaks;
employers with fewer than 50 employees are exempt only if they can prove that complying would cause an undue hardship (significant difficulty or expense), a standard the Department of Labor calls stringent. Airline crewmembers are excluded, and some rail and motorcoach employees have specific exemptions.

Federal law is a floor: many states go further, for example with paid breaks or protections beyond one year, and the FLSA doesn't override them. The Pregnant Workers Fairness Act (employers with 15 or more employees) also covers lactation as a reasonable accommodation, with no set one-year limit, according to the EEOC.

If your employer doesn't respect these rights, the Department of Labor's Wage and Hour Division takes confidential complaints at 1-866-487-9243.

How often should you pump at work?

The CDC's rule of thumb: pump as often as your baby drinks, to keep up your supply. In practice, the Office on Women's Health says you may need to pump 2 to 3 times during a workday, each session taking about 10 to 15 minutes once you're used to your pump. The AAP notes that a drop in supply among working parents most often comes from skipped pumping sessions or sessions that are too short.

At work, the CDC says breast milk can go in the shared fridge with other food, or in an insulated cooler with ice packs for up to 24 hours. Bring it home each day, then use it, refrigerate it or freeze it.

Two more tips: visit the daycare before you go back and ask how they store and prepare breast milk (CDC), and if you can, start back in the middle of the week, for a 2 or 3 day trial before a full workweek (AAP).

Who does what, as a team?

Going back to work is often a two-person job: one parent pumps, the other thaws the right bag, packs the daycare bag and notices when the stash runs low. The simplest system is one shared, up-to-date list of the stash that both of you check before taking a bag out.

In Caasi, each pumping session becomes a numbered batch, in the fridge or the freezer. Both parents see the same milk stash and each batch's use-by time, and the total updates when a bottle is given from the stash.

Frequently asked questions

Are pump breaks at work paid?

Not necessarily. Under federal law, pump breaks don't have to be paid unless you aren't completely relieved from duty during the break, you use a break that's already paid, or a state or local law requires it. A salaried exempt employee's pay can't be reduced for pump breaks.

Can my employer make me pump in a bathroom?

No. The FLSA requires a place other than a bathroom, even a private one, that is shielded from view and free from intrusion. The Department of Labor says the space can be temporary or shared, as long as it's available when you need it.

What should I tell daycare about my breast milk?

The CDC suggests visiting before you go back and asking how the daycare stores and prepares breast milk, and labeling each container with your baby's name. Its guidance for childcare providers recommends bottles of 2 to 4 oz to limit waste and sending unused milk home every day. Rules can vary by state.

How long does a frozen stash keep?

At 0°F or colder, about 6 months is best and up to 12 months is acceptable, according to the CDC. Once thawed in the fridge, milk keeps 24 hours and is never refrozen.

Sources

The guidance in this article comes from the official sources listed above. It doesn't replace advice from your pediatrician, your doctor or a lactation consultant.

When should you start building a breast milk stash?

How much breast milk should you store?

How should you freeze your stash?

Pumping at work: what does the law say?

How often should you pump at work?

Who does what, as a team?

Frequently asked questions

Are pump breaks at work paid?

Can my employer make me pump in a bathroom?

What should I tell daycare about my breast milk?

How long does a frozen stash keep?

Sources

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