Are There Any Advantages Of Mixing Breast Milk with Formula

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While breastmilk is the best milk for young babies it is not always possible for all women to breastfeed and, for many women, formula feeding is the preferred choice.

For many women, mixed feeding is the best option as they want their baby to enjoy breastmilk but would like to enhance it with a formula to ensure that their baby has all of the nutrition they need. 

Many women choose to supplement breastmilk with formula is they cannot be with their baby all of the time, they struggle to express or their baby does not take to feeding from the breast and they naturally find that mixed feeding is a good combination. 

If you are in doubt as to whether or not mixed feeding is the right way forward for you and your baby or you are unsure about how to mix feed, we take you through the pros and cons of mixing breastmilk with formula. 

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Why Mix Breast Milk with Formula?

baby sleep floor

As mentioned, some babies do not take to feeding from the breast or they do not like the taste of breastmilk.

From a woman’s point of view, breast milk production can vary from woman to woman and even a woman who is successful at breastfeeding can have a dip in production. If, for whatever reason, you cannot always feed your baby breastmilk then supplementing it with formula is a great option.

This option is perfect for women who wish to continue breastfeeding when they return to work or are looking to spend some time away from their baby without worrying about how the baby will be fed.

If you are unsure about whether you should try mixed feeding you can speak to your doctor, midwife, or a feeding consultant for advice. 

Should you Mix Breastmilk and Formula in the Same Bottle?

While you can mix breastmilk with the formula it is usually advised that you keep them separate when preparing, so you do not simply mix the formula powder with your expressed breastmilk.

The main reason to keep the two feeds separate as they both have different storage guidelines and you do not want to risk wasting breastfeeding when you have to throw away the formula when it spoils.

Experts also believe that mixing formula and breastmilk in the same bottle can affect the proteins and some of the beneficial elements of breastmilk. As you will want to ensure that your bay gets the nutritional benefits of both breastmilk and formula you should follow the best guidelines for mixed feeding. 

Mixing Breast Milk With Formula

You may be wondering how you mix formula with breastmilk or if you should not put them in the same bottle and we are here to give you the answers.

In order to carefully mix formula and breastmilk you should follow the below steps:

  1. Follow the guidelines on the formula packet to prepare the formula as normal. If you have a ready-mixed formula you can ignore this step. 
  2. Follow CDC advice and use water from a safe source as the formula is not sterile and needs to be mixed with boiling water. 
  3. Once you have prepared the formula you can then mix it with breastmilk at a ratio that your lactation consultant or doctor advised. This mixture can be stored in the refrigerator for up to 24 hours. 
  4. Before you try your baby with their first mixed feed you should try them with formula on its own and with breastmilk on its own. 
  5. For the first bottle, use a little bit of the mixture and keep the remainder in the refrigerator as your baby may not take to the mixed feed straight away and you don’t want to waste any of the mixtures. 

The Pros Of Mixing Breast Milk with Formula 

If you are contemplating mixing formula with breastmilk you can look forward to enjoying the below benefits:

  • It will help your baby adjust to taking formula if that is your long-term goal
  • It will take the pressure of expressing a lot of milk at once if this is something that you struggle with
  • Mixed feeding allows your partner to take part in feeding your baby which may help with the bonding process
  • It can help to wean your baby off the breast if you want to stop breast-feeding for any reason
  • The addition of formula to your breastmilk may leave your baby feeling less hungry and may therefore promote longer sleep sessions as it can take longer to digest than formula milk
  • It allows other people to feed your baby if you cannot be with them to breastfeed and you want them to have breastmilk as well as formula
  • If your baby is not thriving and you believe they are not getting enough breastmilk then it can be topped up with a formula
  • Your baby can still receive the benefits of breastfeeding when enjoying formula feeding
  • Mixed feeding may allow your baby to breastfeed for longer as you can benefit from breastmilk but the strain is taken off you with formula feeding and you will have more freedom to do more things like be with friends or take short breaks

The Cons of Breast Milk with Formula

While there are many benefits of mixing formula with breastmilk there are some downsides, including?

  • You need to follow clear advice from your health professional so that you mix the correct proportions of milk and formula. If the mix is incorrect then you risk your baby not getting the nutrition that they need and becoming dehydrated, especially if you end up making the mixture too watery. 
  • It may not always be possible to express breastmilk
  • You may end up wasting breastmilk if your baby does not take to formula
  • If you reduce the number of times your baby breastfeeds or when you express breastmilk then you may risk decreasing your milk supply
  • If mixed feeding reduces your milk supply you may risk getting inflammatory breast conditions such as mastitis
  • Mixed feeding requires preparation and can then take longer to feed your hungry baby. As well as mixing the feed you will also need to think about sterilizing the bottles 
  • Your baby may take to using a bottle and may begin to refuse your breast. This is something you need to consider if you feed direct from the breast rather than express into a bottle as it may be something you miss, particularly at bedtime. 
  • If your baby does begin to refuse the breast then they may not use the breast for comfort and you may need to offer a pacifier if your baby becomes upset

Alternatives to Mixing Breast Milk And Formula

If your breastmilk is not sufficient for your baby but you find that your baby does not take to a bottle mixed with formula then you can look into combination feeding.

Combination, or partial, breastfeeding as it is also known, involves sometimes feeding your baby breastmilk and sometimes feeding them formula. For example, you may breastfeed your baby in the mornings and at bedtime but feed them formula during the day.

In this scenario, you can feed your baby direct from the breast or you may express and feed them from a bottle, which may be beneficial if they struggle to alternate between a bottle and the breast. Feeding your baby in this way could minimize some of the problems that mixed feeding may bring.

If you do plan on eventually moving to formula full time then you should consult a doctor or a lactation consultant so that you can make the switch without impacting your baby’s nutrition. 

If you need to supplement your breastmilk but you do not want to use formula then you can look for donor milk as an alternative. Depending on the area where you live, donor milk can be difficult to come by so it may not be an option for all. 

If you are concerned about any aspects of breastfeeding you should consult a feeding expert/lactation consultant or a doctor who can review your circumstances and give you advice on the best way forward feeding your baby. 



Mixed feeding is a great alternative to just formula feeding or just breastfeeding if your lifestyle requires the flexibility that it brings. While you should not mix formula directly into a bottle of breastmilk it can be prepared safely using the instructions on the formula bottle and the directions given in this article.

Once the milk is mixed you can feed your baby a mixed drink which can allow your baby to get maximum nutrition. Mixed feeding is just one alternative to a single way of feeding as some parents choose to partially breastfeed and formula feed separately.

If you are ever worried about how much food your baby is consuming or they are losing weight then a lactation consultant can help you overcome your problems by offering safe and effective solutions.