How to Safely Warm Breast Milk

By Ece · Founder of Idaho Jones, pumping mom

Warming breast milk safely, per current CDC and La Leche League guidance

Breast milk is a precious, nutritious resource, and there are times you'll need to warm it before a feeding. Done right, warming keeps the milk's quality intact and makes it more palatable for your baby. Here's how to do it safely, following the guidelines from the Centers for Disease Control and Prevention (CDC) and La Leche League International (LLLI), plus a few practical tips to make it easier.

Why warm breast milk?

Breast milk is perfectly safe to feed straight from the refrigerator or at room temperature. But warming can help in a few situations:

• Sensitive or finicky eaters: some babies prefer warm milk and find it easier to take.
• Expressed milk: if you're feeding previously expressed milk stored in the fridge or freezer (in milk storage bags, for example), warming restores it to a natural temperature.
• Frozen milk: when thawing, gentle warming can improve the taste and make it more appealing.

What the CDC recommends

• Start clean: wash your hands and make sure your containers are clean before handling milk.
• Thaw frozen milk safely, in the refrigerator overnight, in a container of warm water, or under warm running water. Never thaw on the counter at room temperature, and never in the microwave.
• Avoid direct heat: never warm milk on the stove or in the microwave. Both create hot spots that destroy nutrients and can burn your baby's mouth.
• Use warm water or a bottle warmer for even, gentle heating.
• Once milk is warmed or brought to room temperature, use it within 2 hours, and never refreeze thawed milk.

What La Leche League adds

• Warm gradually: avoid sudden temperature changes, which can compromise the milk's nutritional and immunological properties.
• Thawing overnight in the fridge is the gentlest method and preserves the most fat content. Once fully thawed, use the milk within 24 hours.
• Don't reheat the same milk multiple times, which raises the risk of bacterial growth.
• Test before feeding: put a drop on the back of your hand or your inner wrist. It should feel lukewarm, not hot.

Practical tips for warming

• Plan ahead: if you know you'll need warmed milk, move it from the freezer to the fridge the night before for gentle, gradual thawing.
• Warm water bath: fill a bowl with warm (not boiling) water and set the sealed container in it, swirling occasionally for even warming. Give it a few minutes.
• Bottle warmers: these heat milk and bottles gently and safely. Follow the manufacturer's instructions and always test the temperature before feeding.
• Avoid hot water: use warm, not hot. Hot water damages nutrients and immunological components. Aim for around body temperature (about 98.6°F / 37°C).
• Never boil or refreeze: extreme temperatures destroy the milk's beneficial properties. Stick to gentle warming.
• On the go: you don't need an electric warmer. Keep your milk cold in an insulated cooler until you're ready, then warm it with a cup of warm water and test before feeding.

From Idaho Jones

Keep milk cold until you're ready to warm

The Roxwell cooler holds up to four bottles with insulated, leakproof walls and pockets for ice packs. Out at work, daycare, or travel, your milk stays safely chilled until it's time to warm it.

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The bottom line

Warming breast milk is simple when you follow the CDC and La Leche League guidance: use clean containers, thaw gently, skip direct heat, and warm with warm water or a bottle warmer. Always test the temperature so it's lukewarm, and use warmed milk within 2 hours. Do that, and you'll keep your milk safe and nourishing for your baby.

References:

1. Centers for Disease Control and Prevention. Breast Milk Storage and Preparation. cdc.gov
2. La Leche League International. Heating Human Milk. llli.org
3. Mom Loves Best. How to Reheat Breast Milk Safely. momlovesbest.com
4. Exclusive Pumping. How to Warm Breast Milk. exclusivepumping.com