Supplementing formula while breastfeeding: everything you need to know

Hey mama, we get that you’re probably here because breastfeeding isn’t going as well as you’d hoped, or maybe you’re just ready to explore your feeding options. Whatever the case, if you’re interested in starting formula feeding, or supplementing your breast milk with formula, you’re not alone. A 2019 survey by Mamava found that 42 per cent of moms surveyed had supplemented with formula at some point in their baby’s first year. 

Breastfeeding is really f*cking hard. 

For most, it’s not the natural, magical experience you may have been led to believe it would be. And that makes sense when you think about it, given you’ve never done it before, and neither has your baby. There are many different ways it can go wrong and many reasons women decide to switch from breast milk to formula. But did you know you can do a bit of both?

Introducing combination feeding, where you supplement with formula while continuing to breastfeed. And now you know it’s an option, we’re sure you have questions. We sure did – so we sat down with the brilliant Susie Prout, an Australian Registered Midwife, International Board Certified Lactation Consultant and mother of three, to get all the answers on supplementing with formula while breastfeeding.

Should you supplement with formula?

There are plenty of reasons why you may choose to introduce formula while breastfeeding, either by personal choice or under advisement from your pediatrician. Including:

  • Your baby isn’t gaining enough weight
  • You’re experiencing difficulty with breastfeeding
  • You are experiencing low supply
  • You are taking medications that affect your breast milk
  • You are returning to work
  • You no longer want to breastfeed.

Deciding to supplement with formula is a very personal decision and it’s important to remember that your mental health is just as important as the nutritional benefits that breast milk provides your baby. Any way in which you choose to feed your baby is valid.

How do you know if your baby is getting enough breast milk?

One of the main reasons breastfeeding mamas choose to stop breastfeeding or start supplementing with formula is because they feel they aren’t producing enough milk. Susie explains that there are many myths surrounding signs of low milk supply, including:

  • A lack of fullness in the breasts
  • An unsettled baby
  • Low output when using a breast pump
  • How often and for how long your baby is breastfeeding

We get it, the mom anxiety is REAL – you just want what’s best for your baby and this can leave you questioning yourself.

“The best and most reliable way to tell if your baby is getting enough breast milk is by weighing your baby, and your health professional plotting your baby’s weight on their growth chart to look at the growth curve,” advises Susie. 

It’s important to note that not all babies gain weight at the same pace, so it’s best to have a professional look at your baby’s weight gain over certain periods of time.

Other signs your baby’s doctor or pediatrician may look for include:

  • Your baby’s stool and whether they have an adequate amount of wet diapers
  • “Level of satisfaction and how content your baby is after a feed is also looked at, but not on its own. The weight is the gold standard.” Susie explains. 

Susie also warns against giving your baby formula because you are worried they aren’t receiving enough milk without evidence of low supply, as this will increase your risk of stopping breastfeeding – something you’ll want to avoid if continuing to breastfeed is important to you.

“If you have any concerns about your milk supply, your best bet is seeing your maternal child health nurse or a lactation consultant for a review”.

Mumli tip: You can use this database to search for lactation consultants in the U.S.

Introducing formula to your baby

If your baby has been breastfed up to this point, they may be quite attached to your boobs, and less than impressed when you present them with a bottle. In fact, there are a number of reasons your little one might refuse the bottle, including:

  • They aren’t hungry at the time you offer it
  • They’re feeling sick, or uncomfortable
  • They’re being held in a position that feels uncomfortable
  • They don’t like the flavor or texture of the milk, or the temperature isn’t right
  • They don’t like the shape or feel of the bottle nipple
  • They simply prefer the boob

“Breastfeeding is also so much more than just nutrition,” Susie explains. “Babies breastfeed to feel close, to sleep, to feel comfort, when they’re sick, and when they’re in pain – so all these things can cause a baby to reject a bottle.” 

Here are her tips to help nudge them along:

  • Trying when they are tired, or not tired, hungry, or not hungry
  • Have someone else try and feed them with a bottle
  • Try walking around with them while feeding so that they have a distraction
  • Keep trying on a daily basis so they become familiar with the bottle
  • Use a bottle with a long stretchy teat, so it most resembles a nipple 
  • Keep trying with the same bottle/nipple so they aren’t further confused with lots of different teats.

Unfortunately, these aren’t a guarantee of success. “It can take weeks of trying every day to get any success. Many babies will accept the bottle in time, but some babies will always refuse a bottle. If they are over six months, they may prefer a sippy or straw cup with milk in it.”

Mumli tip: According to the American Academy of Pediatrics, if your baby is six months or older, they may also be ready to start solid foods. If your older baby won’t take the bottle, starting them on solid foods might help gradually reduce the amount of breastmilk required in your baby’s diet. Remember it’s important to start slowly, and discuss introducing solids with your family doctor or pediatrician before you begin.

Frequently asked questions

1. Will supplementing with formula reduce the benefits of breast milk? 

It is true that breast milk is full of beneficial live ingredients that formula doesn’t contain, which help fight off infection and build your bub’s immunity. 

Cool fact: when breastfed babies are sick, your body will produce specific antibodies to combat whatever infection they’ve picked up, and deliver those antibodies through your breast milk while breastfeeding. Wild.

The great news is that by choosing to continue breastfeeding while introducing formula, you’re ensuring your little babe still reaps the rewards breast milk has to offer. 

“The more breast milk you give your baby, the more of a benefit they’ll receive,” assures Susie, “but it’s important to remember that if you are mixed feeding with both, the breast milk your baby receives is still beneficial.”

2. Can you mix breast milk and formula?

Technically yes, you can mix formula and breast milk in the same bottle, as long as you adhere to some guidelines for safe formula feeding, including making sure you maintain the correct ratio of water to formula and then add breast milk separately.

Susie advises to avoid mixing the two though, and instead, breastfeed or give expressed breast milk first and then follow with formula. We agree with her reasoning:

  • There is a risk you may make a mistake with mixing the formula and then mixing the breast milk together.
  • If you mix them together and your babe doesn’t take the whole bottle, then you’ve wasted breast milk, as you’ll have to throw it away.

If you’re the type of mama who might mess up her ratios at 3am when you’re a sleep-deprived mess (i.e. all of us) or you’re simply not willing to risk wasting your precious liquid gold if your baby doesn’t finish the bottle (again, all of us) it just ain’t worth it. Keep them separate and make sure your baby gets all that breast milky goodness before topping up with formula if they’re still hungry.

3. Can you use formula for a short period and then return to exclusively breastfeeding? 

Maybe you need to spend a night or two away from your little one for a work trip, or a girl’s weekend away – we really hope it’s the second one! Or you might be temporarily unable to breastfeed due to a medication you’re taking, under your doctor’s advice. 

Whatever the case, we’re happy to say that you can take a short break from breastfeeding and then return to nursing your baby. Susie gave us a few tips to make the whole process a bit easier for both you and your babe.

Get them used to the bottle

If your babe has been exclusively breastfed up to this point, Susie recommends introducing the bottle to your baby well before your anticipated break, to make sure they’ll be comfortable taking it when the time comes.

“You may need to practice a bit before they’ll accept the bottle. Also, if you’re giving formula rather than expressed breast milk it’s important to try the formula so you know your baby will accept it and doesn’t become too unsettled with the new milk.”

Express regularly while you’re away

Susie also suggests expressing regularly to keep your supply up while you’re not nursing. She recommends trying a hospital grade double electric pump and pumping around the same times your baby usually feeds.

Reintroducing breastfeeding

“It may take a little while for your baby to accept the breast again” Susie warns, so have patience mama. Spend some time doing skin to skin with your baby and let them feed on demand to get you both back on track.

4. What if your baby starts losing interest in breastfeeding?

Within her practice, Susie has found that giving one bottle in 24 hours doesn’t usually affect breastfeeding (in terms of breast refusal), but warns, “The more bottles you give, the more chance your baby will start to refuse the breast.” So be warned, if you are feeding your babe multiple bottles of formula every day, there’s a chance it may lead to nipple confusion, or a preference for bottles.

Mumli tip: Pace feeding is a method of bottle feeding that aims to mimic the slower pace of breastfeeding and may help reduce the likelihood of your baby developing a bottle preference. 

Using a slow flow nipple, hold the bottle at parallel to allow for better flow control. Listen carefully to when your baby sucks, and pull the bottle back slightly to give your baby short breaks every 5-10 swallows.

5. How do you maintain your milk supply?

The less often you breastfeed or pump, the more likely you are to experience a drop in supply, because breast milk is made by the body on a supply and demand principle. So efficient, these bodies of ours.

Susie warns that it can be easy to fall into the ‘top up trap’, which happens when moms feel like they don’t have enough milk for their baby, so they ‘top up’ with formula. Their babe is then full, sleepy and breastfeeds less often.

“Babies feel more full with formula for longer because of the density of formula compared to breast milk. Then because there is less stimulation at the breasts, your milk supply decreases.”

The cycle then continues when your baby tries feeding at the breast again and can’t get a full feed, and your supply continues to drop until it is too low. Eep!

Susie recommends chatting with your child care health nurse or lactation consultant to set up an individualized plan, help prevent your milk supply from suffering too much and work with you to increase your milk supply if needed. 

Mumli tip: Check out our top tips for pumping.

A very important final tip

Whether you breastfeed, formula feed, exclusively pump or combination feed – the way you feed your baby does not determine your worth as a woman, or as a mother. It’s important that you choose the option that’s going to work best for you and your family. 

Feeding babies is hard work, no matter how you do it – you’re doing a great job mama.

And remember, the information included in this article does not replace medical advice, so if you’re ever unsure, pay a visit to your doctor or family physician.

You’ll find more helpful tips, high fives, and encouraging pats on the bum on Mumli, your pocket-sized personal assistant for all things motherhood – coming to your home screen soon. Join the waitlist now.

Expert contributor: Susie Prout

Susie is a Registered Midwife and International Board Certified Lactation Consultant. Susie lives in Perth with her husband and 3 small children. She runs a private lactation consultancy business as well as an online Breastfeeding Sucess Membership and program to teach new mamas and pregnant ladies how to successfully breastfeed with ease.

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