Your guide to combining formula with breastfeeding.
I spoke with a mom today who has combo fed her 2 children, and is passionate about helping other parents who want to do the same. Combo feeding is when you breastfeed (or pump) AND formula feed, in any combination, either by choice or necessity.
She and I had a really honest conversation about the pressure parents feel to exclusively breastfeed, and the lack of support to help them achieve that. The reality is that over half of babies receive formula at some point in the first 6 months of life.
But despite how common formula use is, most parents never receive information from their caregivers on how to use it safely.
The lack of information on formula and our messaging about exclusive breastfeeding leads to stigma. Parents don’t always feel safe asking their baby’s providers about formula, for fear of being shamed about not exclusively breastfeeding.
Here are some quotes from a study on parents’ experiences of formula feeding:
“No one helped me, and everyone was just nagging about how good it is to breastfeed.”
“The inconsistent guidance and support was frustrating and confusing.”
“It’s difficult to do what is the opposite of the culture.”
The thing that I’ve learned as a nurse and a lactation consultant is that there is no one-size fits all approach to anything, and this is certainly true of infant feeding.
My goal here is to try to take the shame and guilt away from formula use, and to provide practical information on how to use it safely. I want you to get support no matter how you’re feeding your baby.
Human milk is made for human babies. But exclusive breastfeeding is not always possible, nor is it always desired, and all parents deserve nonjudgemental, quality support and information.
“Any formula that you give your baby doesn’t negate the benefits of breastfeeding. ”
What about milk production?
If your goal is to make as much breastmilk as possible, I recommend pumping and/or hand expressing when your baby takes formula. This will help you to build up or maintain your production. If that’s not your goal, no worries. Just be aware that your body will produce only enough to replace what baby drank from you.
Combining breastfeeding and formula feeding.
There are several ways to do this, and there is no one right way for all families. Here are some options:
🍼 Start with breastfeeding, finish with formula.
This is often referred to as “topping up”, because you’re giving your baby the available breastmilk, then offering formula to finish the feeding. The formula can be given in a bottle, but if the amounts are relatively small, a cup or syringe may be a good choice.
🍼 Start with formula, finish feed at the breast.
This is helpful for a few reasons: 1) A hungry baby doesn’t always breastfeed well, so giving an “appetizer” can allow your baby to do a better job when they get to the breast, 2) Your baby fills up on breastmilk and associates feeling full and satisfied with breastfeeding.
🍼 Breastfeed for some feeds, formula feed for others.
This can be done in any way that works, but a common approach is to breastfeed during the day, and use formula for one or more evening feeds. This approach can allow the breastfeeding parent to get a slightly longer stretch of sleep. For some, a 5 hour uninterrupted chunk of sleep can be a huge help in maintaining mental health.
Using the Medela supplemental nursing system (SNS).
🍼 Feed formula through a supplemental nursing system (SNS) while breastfeeding.
There is a bit of a learning curve with this device, but it’s an excellent choice for parents who want most, if not all, feeds to be at the breast.
An SNS: 1) helps build up milk production because baby is at the breast more often, 2) gives your baby more time to practice breastfeeding, 3) prevents the need for bottle feeding in addition to breastfeeding. Here’s more information on using this type of system.
Bottle feeding basics.
How you give the bottle is important. I recommend using a responsive aka paced bottle feeding technique. This helps with:
✅ preventing overfeeding
✅ preventing gas and spitting up
✅ aids in good oral development by encouraging baby to use their muscles to draw milk out, rather than allowing milk to flow passively
✅ preventing the development of a fast flow preference, which can negatively impact breastfeeding
Here is a good video on using this approach:
As mentioned in the video, a nipple with a more gradual slope from base to tip will be a better choice for most babies. This shape promotes deep latching and effective sucking, which we also need for breastfeeding. Evenflo, Pigeon and Lansinoh make my current favorite bottles.
How to buy and prepare formula.
There are 3 ways to purchase formula:
Sterile, liquid formula in bottles (aka ready to feed).
Concentrated liquid formula (must add water to dilate before feeding).
Powdered formula in cans (must be combined with water before feeding).
Why would you choose one type over another?
Typically this comes down to your preference and what’s within your budget. Here are some pros and cons to consider:
Liquid formula
✅ Pros: Quicker to prepare, as it’s either ready to feed or just needs water to dilute it. Since liquid formula is sterile until it’s opened, this is considered the safest option for babies at higher risk for getting sick from bacteria, such as a baby who was born prematurely, those with weakened immune systems and those under 2 months.
❌ Cons: More expensive and creates more waste.
Powdered formula
✅ Pros: The most affordable and accessible choice.
❌ Cons: More time-consuming to prepare and easier to make mistakes with preparation. It can contain harmful bacteria, as it is not a sterile product.
Here’s more information from the AAP on choosing formula.
How to prepare powdered formula.
Your hands should be washed and bottles and nipples should be sanitized. See this article for more information.
Read the directions on your formula container. Generally the mixture will be 2oz (60ml) of water per level scoop of formula, but always double check this to be sure.
Measure out your water in the bottle.
Add the formula powder to the bottle.
Shake until completely dissolved.
Feed within 2 hours of preparing the bottle, or refrigerate for up to 24 hours.
Discard leftover formula within 1 hour of starting the feeding.
NEVER warm formula or expressed milk in the microwave! This can create hot spots which can burn your baby’s mouth. The best ways to warm milk are:
1) under warm running water
2) in a bowl of warm water
3) in a bottle warmer.
FYI, not all babies need warmed milk or formula. If your baby is happy to drink cold or room temperature milk, no problem!
Here’s more information from the CDC.
What about boiling water?
If your baby is less than 2 months, has a weakened immune system, or was born prematurely, they’re at more risk from bacteria that may be present in powdered formula.
In order to provide protection from this bacteria, it is advised that you boil your water and combine the hot (but not boiling) water with the formula, then cool the prepared formula before feeding it to your baby.
The best way to check the temperature of the formula is to place a drop on your wrist. The milk should not feel warmer than body temperature.
Get more information here.
How to combo feed expressed milk and formula:
There is no one right way to do this, but here are a few approaches:
Pumped breastmilk and formula in separate bottles.
✅ Pros: Since breastmilk has a longer shelf-life than formula, less is wasted with this approach. Refrigerated expressed breastmilk can be used for up to 4 days. Prepared refrigerated formula should be used within 24 hours.
❌ Cons: More time consuming since multiple bottles are prepared.
Combine pumped breastmilk and formula in one bottle.
✅ Pros: More convenient since one bottle is prepared.
❌ Cons: The bottle must be used within 1 hour of starting the feed
How much formula should I give my baby?
In the first few days of life, your baby needs very small amounts. Here are guidelines from the Academy of Breastfeeding Medicine from their protocol on supplementation:
First 24 hours: 2-10ml (up to 2 tsp)
24-48 hours: 5-15ml (1 tsp-0.5oz)
48-72 hours: 15-30ml (0.5-1oz)
72-96 hours: 30-60ml (1-2oz)
By one month of age, most babies are taking 2-4oz per feed, or between 25 and 35 ounces over 24 hours. This number stays the same for babies who are only getting breastmilk, but formula fed babies will need more over time.
If your baby is also breastfeeding, you won’t know how much they’re getting at the breast, so it’s a good idea to start with a small amount of formula and observe your baby’s cues. If your baby appears happy and relaxed, they’ve probably had enough. If your baby is still searching for more, you should give a bit more.
It’s incredibly important to pay attention to your baby’s hunger and fullness cues. If you have concerns about the number of wet and poopy diapers your baby is making, or your baby’s behavior, always call your baby’s provider to discuss it.
For good books on this topic, I recommend Mixed Up! by Lucy Ruddle, Feeding Your Baby Boob, Bottle & All by Olivia Hinge and Feed the Baby by Victoria Facelli.
If you want 1:1 support, reach out to a lactation consultant who’s supportive of all infant feeding choices. You and your family deserve compassionate and knowledgable care.
For more information, check out some of my other blog posts:
