Bringing a baby into the world is one of the most beautiful and overwhelming experiences you’ll ever have. As a new parent, you want to make sure your little one is getting the best nutrition possible. But sometimes, exclusive breastfeeding isn’t an option, and that’s okay. Maybe your milk supply is low, or you need the flexibility of formula feeding due to work or other commitments. Whatever the reason, mixing breast milk with formula can be a great way to ensure your baby is fed and happy.

I remember when my sister had her first baby she was determined to breastfeed exclusively but soon realized her milk supply wasn’t keeping up with her son’s needs. She felt guilty and stressed, wondering if supplementing with formula would mean she was failing as a mom. If you’ve felt this way, let me reassure you: you’re doing great! How you feed your baby is not as important as ensuring that your baby gets all the necessary nutrients and vitamins to help them grow strong and healthy. Feeding your baby—whether it’s breast milk, formula, or both is what matters most.

Now, let’s get into how you can safely and effectively mix breast milk with formula.

Why Mix Breast Milk with Formula?

There are several reasons why parents choose to combine breast milk with formula:

• Low Milk Supply – If you’re struggling with producing enough milk, supplementing with formula ensures your baby gets enough nutrients so you don’t have to worry about lack of production.
• Convenience & Flexibility – If you’re returning to work or can’t always pump, formula can help fill in the gaps.
• Shared Feeding Responsibilities – If you want your partner or a caregiver to help with feedings, mixing formula with breast milk allows them to be more involved.
• Weight Gain Concerns – Some babies may need extra calories that formula can provide.

No matter your reason, know that mixed feeding (also called combination feeding) is a perfectly healthy choice for your baby.

How to Mix Breast Milk with Formula Safely

Please remember that before starting this process it is imperative to know that formula must always be prepared separately before being mixed with breast milk. Formula powder is not sterile, and adding it directly to breast milk can create an unsafe environment for your baby. Here’s the proper way to do it:

Step 1: Prepare the Formula

• Follow the instructions on the formula container carefully.
• Use the correct water-to-formula ratio to avoid making it too concentrated or too diluted.
• Use warm, previously boiled, or sterile water for safety.
• Shake or stir the formula well to dissolve all the powder.

Step 2: Cool the Formula

• Let the prepared formula cool to room temperature before mixing it with breast milk. This helps preserve the nutrients in the breast milk, as high heat can break them down.

Step 3: Mix with Breast Milk

• Pour the right amount of breast milk into the bottle with the cooled formula.
• Swirl the bottle gently—don’t shake, as this can break down the proteins in breast milk.

Step 4: Feed Your Baby

• Once mixed, give it to your baby within two hours at room temperature or store it in the fridge for up to 24 hours.
• Never reheat mixed milk in the microwave, as it can create hot spots. Instead, place the bottle in a warm water bath.

How to Transition to Mixed Feeding

If you’re switching from exclusive breastfeeding to a combination of breast milk and formula, your baby might need some time to adjust. It is important to gradually transition into mixed feeding. Here are some tips to make the transition smoother:

• Start with One Bottle of Formula a Day – Let your baby get used to the taste and feel of formula before gradually increasing the amount. Please take this step in particular little by little.
• Mix Small Amounts at First – If your baby is hesitant, try a ratio of 75% breast milk and 25% formula, then slowly adjust.
• Maintain a Consistent Routine – Offer mixed bottles at the same time each day to help your baby adapt.
• Use the Right Nipple Flow – Some babies struggle with faster-flow nipples. Make sure the bottle’s nipple mimics breastfeeding to avoid confusion.
• Pay Attention to Digestion – If your baby becomes gassy, fussy, or has changes in their poop, you might need to adjust the formula brand or type.

Common Concerns About Mixing Breast Milk with Formula

Will My Baby Get Enough Nutrients?

Yes! Both breast milk and formula provide the essential nutrients your baby needs to grow. Mixing them properly ensures your baby is getting balanced nutrition.

Can I Mix Powdered Formula Directly into Breast Milk?

No. Powdered formula must be mixed with water first before adding breast milk. Mixing formula powder directly into breast milk can make it too concentrated, which can be hard on your baby’s kidneys.

Will My Baby Reject Breastfeeding After Using Formula?

Some babies experience “nipple confusion,” but many switch between breast and bottle without issues. If your baby is hesitant, try using a slow-flow nipple to mimic breastfeeding.

How Long Can I Store a Mixed Bottle?

If refrigerated, use within 24 hours. If left at room temperature, discard after two hours.

Can I Switch Back to Exclusive Breastfeeding Later?

Yes, that is always possible! If you can produce a sufficient amount of milk and your baby is willing, you can gradually remove formula and return to exclusive breastfeeding.

Don’t Feel Guilty, Every Feeding Journey Is Unique

At the end of the day, fed is best. Whether you’re exclusively breastfeeding, exclusively formula-feeding, or doing a mix of both, what matters most is that your baby is healthy and thriving.

I’ve seen so many moms, including my very own best friend, struggle with the guilt of supplementing with formula. They may feel bad about not being able to produce enough milk but that is okay. If you may feel guilty then please always keep in mind that there’s no single “right” way to feed a baby. The best way is the one that works for you and your family.

So, if you’re mixing breast milk with formula, know that you’re making a loving and thoughtful choice. Your baby will not know the difference and the most important thing is that your baby get all the necessary nutrients that they need to grow strong and healthy.

If you have any concerns, always check with your pediatrician to make sure your baby is getting what they need. But most importantly, trust yourself—you’re doing an amazing job!