Can I Mix Breast Milk and Formula? Yes, Here’s How.

As a mom, ensuring that your baby gets the right nutrition is one of your very top priorities. Breast milk and formula are two main sources of nutrition for babies, and in some cases, it may be necessary to mix them. This can be confusing and overwhelming. This article provides a comprehensive guide on how to mix breast milk and formula.

To begin with, it’s preferable to do separate feedings with breast milk and formula. We have an entire article dedicated to Supplementing With Formula: Advice from Experienced Moms that outlines everything you need to know about supplementing with formula in this manner. Sometimes, though, you find yourself in a situation where you need to mix breast milk and formula in one bottle.

Should I Mix Breast Milk and Formula?

Mixing breast milk and formula is usually done for two reasons:

1. To supplement breast milk supply
2. To help transition from breast milk to formula

Breast milk is the ideal source of nutrition for babies, but in some cases, it may not be enough to meet the baby’s needs. For example, if you’re going back to work, you may not be able to pump enough milk to last throughout the day. Or, you may need to leave your baby for a few hours from time to time. Pumping may not be an option for a short period of time, but you still need to leave a bottle for your baby. Supplementing with formula can help ensure that your baby gets the nutrition they need.

Related article: The 5 Best Formulas for Supplementing While Breastfeeding

Another reason to mix breast milk and formula is to transition from breast milk to formula. Some moms may choose to wean their baby off breast milk gradually, which involves gradually replacing breast milk with formula. In these instances, mixing breast milk and formula can help ease the transition for the baby and prevent digestive issues.

Pros and Cons of Mixing Breast Milk and Formula

As with every parenting decision, there are several pros and cons of mixing breast milk and formula. Some of the pros include:

1. Flexibility

Mixing breast milk and formula can give parents the flexibility to feed their baby when they need to. This can be especially helpful if you are returning to work and cannot breastfeed as frequently. Additionally, if a breastfeeding mom needs to be away for an extended amount of time either during the day or for several days on a trip and can leave some breast milk, mixing breast milk and formula can provide the additional calories and nutrients your baby needs. This has the added benefit of reliving pressure a mom may feel to constantly pump while away from her baby.

Related article: Pumping on the Go: A Guide to Pumping in the Car Safely and Discretely

2. Nutrient Balance

By mixing breast milk and formula, parents can ensure that their baby is getting a balance of nutrients from both sources. This is especially beneficial for moms who struggle with their babies weight or for babies who have certain medical conditions. Knowing the exact amounts of calories, vitamins, and minerals your baby receives through breast milk and formula can provide peace of mind.

3. Easier Transition from Breast Milk to Formula

Mixing breast milk and formula can make it easier for a baby to transition from breast milk to formula. This can be especially helpful if a baby is having trouble latching or feeding from the breast. Many babies are sensitive to changes in taste. If your baby is already receiving formula with their breast milk and is therefore accustomed to the taste of it, transitioning baby to solely formula should be a smooth transition.

Related article: How to Stop Pumping (Finally!)

While there are benefits to mixing breast milk and formula, there are also some risks that parents should be aware of. Some of the cons of mixing breast and formula include:

1. Wastes Breast Milk

Mixing breast milk and formula can waste breast milk if the baby doesn’t finish a mixed bottle. Bottles should be consumed within two hours of being mixed, otherwise the bottle should be thrown out. Mixing breast milk and formula can result in throwing out your precious liquid gold.

Related article: Do I Need to Pump at Night When Baby Sleeps Through the Night?

2. Digestive Issues

Some babies may have difficulty digesting a mixture of breast milk and formula, which can lead to digestive issues such as constipation, gas, or diarrhea. This can oftentimes be resolved by changing the formula you are using. Check to see what type of formula you are using (soy, whey, etc.) and change to another if necessary.

3. Reduced Breast Milk Production

If a mom regularly mixes breast milk with formula, her milk supply may decrease over time. Breast milk supply is supply and demand. If you skip breast milk feedings or pump sessions due to using formula, your body will naturally decrease the amount of breast milk you produce over time.

Related article: 10 Reasons for a Sudden Drop in Milk Supply (and What to Do About It!)

How to Mix Breast Milk and Formula

Now that we’ve got the pros and cons to mixing breast milk and formula out of the way, here is a step-by-step guide on how to mix breast milk and formula in a baby’s bottle:

1. Ensure that you have the right supplies

You’ll need a bottle, breast milk, and formula. You’ll also need to ensure that your hands are clean and that the bottles and nipples are sterilized.

Related article: 10 Tips on How to Work From Home with Kids

2. Identify the correct ratio of breast milk to formula

This is an important step. The ratio of breast milk to formula will vary depending on your baby’s age and feeding requirements. It will also vary depending on how much breast milk you have. You will need to identify the minimum amount of formula you need to mix up. All of this will be specific to your baby. For example, if your baby needs a 5 ounce bottle and you have 3 ounces of breast milk to use, make sure to measure the appropriate amount of formula and water to make up the remaining 2 ounces.

If you are unsure on the size of bottles your baby needs or what ratio of breast milk and formula to use, it’s best to consult with your pediatrician.

3. Measure the required amount of breast milk

Measure the required amount of breast milk as per your baby’s feeding requirements as identified above, and pour it into the bottle. If you’re mixing breast milk and formula, it’s important to use freshly expressed breast milk. This is because breast milk changes in composition as it ages, and mixing it with formula may affect its nutritional value.

Related article: Breast Milk Lipase: Why Your Breast Milk Tastes Metallic

3. Measure the required amount of formula

Measure the required amount of formula as per your baby’s feeding requirements and mix it with warm water according to the instructions on the label. Different formulas may require different amounts of water, so it’s important to follow the instructions on the label to ensure that you mix the formula correctly.

4. Add the formula to the bottle and shake.

Once you have mixed the formula, add it to the bottle containing the breast milk. Gently shake the bottle to ensure that the breast milk and formula are mixed thoroughly.

Related article: How to Lose Weight While Breastfeeding Without Affecting Milk Supply

5. Check the temperature

Before feeding the bottle to your baby, check the temperature of the mixture to ensure that it’s not too hot or cold. If it’s too warm, allow it to cool. If it needs to be warmed, run the bottle under warm water.

How Long is Breast Milk and Formula Mixed Good for?

A bottle of breast milk and formula mixed together should be used within 1-2 hours. This is why we recommend waiting until right before your baby’s feeding to mix a bottle of breast milk and formula. According to the CDC, you can mix formula and breast milk and store it in the fridge, but it needs to be used within 24 hours. You will need to gently shake the bottle to remix the breast milk and formula prior to using it.

Related article: Baked Oatmeal: The Lactation Version

While you can mix formula and breast milk and store in the fridge, we recommend storing breast milk and formula separately when possible since breast milk and formula have different storage requirements:

Breast milk:

• At room temperature (up to 25°C or 77°F): 4 hours
• In a cooler bag with ice packs: 24 hours
• In the back of a refrigerator (not in the door): 3-5 days
• In a freezer compartment within a refrigerator: 2 weeks
• In a stand-alone freezer: 6-12 months

Formula:

• At room temperature (up to 25°C or 77°F): 1 hour
• In a cooler bag with ice packs: 24 hours
• In the back of a refrigerator (not in the door): 24 hours
• Any formula left in the bottle after feeding should be discarded within 1 hour.

Mixing breast milk and formula can help ensure that your baby gets the nutrition they need. Whether you’re supplementing breast milk or transitioning from breast milk to formula, it’s important to follow the above steps to ensure your baby is happy and healthy. And remember fed is best!