Combining Breast and Formula Feeding for Your Baby

Woman feeding a baby at a sidewalk cafe

Gary John Norman / Getty Images

One of the most fascinating aspects of breastfeeding is that it works on a supply and demand system. In other words, your body "learns" how much your baby will need to eat and will produce that much milk. Of course, it can take time for your body to provide the milk supply that your baby needs. Different factors, such as genetics, diet, stress, or illness, affect your supply as well.

In some cases, a person who is breastfeeding might need to supplement breast milk with formula. Whether for personal preference or another reason, if you are hoping to combine breast and formula feeding, your body will adapt. If and when you do want to increase your milk supply, here are a few tips.

Establish Breastfeeding First

It's best to start off with exclusive breastfeeding even if you know that will you will want to add formula later on. Not only does exclusive breastfeeding help ensure that your baby learns how to effectively breastfeed, but it will also help you to establish an adequate milk supply.

It's easier to taper down your supply when you're ready to add in formala feedings than it would be to try to get your body produce more milk. If you add formula right away, your body might not make enough milk. Additionally, your baby might not suckle effectively enough, which will further discourage milk production and can leave you both frustrated.

Exclusively breastfeeding for four to six weeks will help you build up your supply and establish a good breastfeeding routine with your baby.

Drop Breast Feedings One at a Time

If breastfeeding has effectively been established and you would still like to continue with mixed feedings, start by eliminating one breastfeeding at a time and replace it with a formula bottle. You might find it convenient to replace a nighttime feeding with a bottle, which would allow your partner or another caregiver to feed the baby and give you some much-needed rest.

You can also hand-express extra milk to prevent engorgement—just be careful not to stimulate your breasts too much (as this can make you produce more milk).

Be Flexible

You might have to experiment with different types of bottles or formulas to help your baby adapt to mixed feedings. Your baby might prefer breast over a bottle at certain times of the day. For example, you might have a harder time getting your baby to take a bottle when they are sleepy because they want the breast for comfort.

You might have to try different times of the day before finding a routine of mixed feeding that works well for everyone.

Be Prepared for Changes in Your Baby

When you introduce a strictly-breastfed baby to formula, it can cause some changes to their bowel movements. Breast milk and formula have different compositions. For example, breast milk has a very different microbial make-up than formula.

Don't be alarmed if if your baby's poop suddenly changes color or smells different after they start taking formula feedings—this is normal! However, if your baby is spitting up more, gets constipated, or seems uncomfortable, you'll want to check with your healthcare provider about whether mixed feedings are right for your baby, or if they need to try a different formula.

2 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Nielsen SB, Reilly JJ, Fewtrell MS, Eaton S, Grinham J, Wells JC. Adequacy of milk intake during exclusive breastfeeding: a longitudinal study. Pediatrics. 2011;128(4):e907-914. doi:10.1542/peds.2011-0914

  2. Guaraldi F, Salvatori G. Effect of breast and formula feeding on gut microbiota shaping in newbornsFront Cell Infect Microbiol. 2012;2:94. doi:10.3389/fcimb.2012.00094

By Chaunie Brusie, RN, BSN
Chaunie Brusie is a registered nurse with experience in long-term, critical care, and obstetrical and pediatric nursing.