Breastmilk With Formula
Can you mix the two? The short answer, is NO. Is that not the answer you were looking for? Probably not. Did you see the opposite on google? I know. But let’s remember that Dr. Google is a SCARY place to be. Free advice from random people on the internet? Not when it comes to your baby. Sure we ALL google- I mean, isn’t that what it’s for? But, say it with me, ‘Not when it comes to your baby.’
Questions concerning what our babies eat, where and how they sleep, and other potentially life-altering issues should ALWAYS be left up to a professional. And one you trust. If you’d like to learn more about me, please check out my about page! But in a nutshell, I’ve been in the lactation world for 6 years, I am an International Board Certified Lactation Consultant, a Mother, I’ve worked in the Hospital as well as private practice and I am also a perpetual student. I pride myself on staying in the know and up to date on all things lactation through online webinars, reading published medical studies and discussing topics (such as this one) with my professional peers. Now back to the mixing shenanigans.
Formula was developed to be a breastmilk substitute and it needs to be used as just that. A substitute for milk, not an additive or fortifier. Now there are human milk fortifiers that you can use IF directed by your pediatrician but chances are, unless your infant was born less than 3.5 pounds, you do not need to go this route. Likely the reasons we, as Mothers, use formula will vary. It could be a low supply, returning to work, slow weight gain, etc. but the way in which we use it, should be uniform, across the board. On EVERY formula container (whether premixed liquid or ready to mix powder) there are specific and easy to read directions for use. The directions are there for a reason and should be followed to a T without exception.
I feel the need to stress this importance a little further. Join me on this wormhole ( it will be quick I promise.) Okay so let’s take Similac for instance. Similac is a well know heavy hitter in the formula industry. When you google “Can you mix breastmilk with formula Similac” it will bring you here. Now, when you scroll about half way down you’ll see the section on ‘Supplementing Breastmilk With Formula” and it says you “can” mix them and ‘click here’ for a guide. And when you do, it instructs you to yet again click here for more on how to make a bottle which brings you right back to our original link. It’s an actual HAMSTER WHEEL of misinformation with no facts. You can also see that on the Enfamil, another heavy-hitting brand’s website it states, “Human milk fortifier is the only product intended to fortify breast milk, as the Enfamil A+ fortification recipes below are provided as a courtesy. They are based on calculated results of mixing—they are not clinically or analytically tested.” So, they first say they recommend fortifying milk with formula but then state they have no proof as to why or how to safely do that. Things that make you go Hmmmmm…
Worried about calories?
Maybe you have multiples. Or maybe your baby is struggling to meet their growth chart expectations. Sometimes, we stress about our infant’s intake which is a natural concern! And, if you’re not able to meet your infant’s demands with breastmilk, formula use is a great bridge to help fulfill infant’s needs. But, where we see a common misconception, is when we think breastmilk and formula are one in the same. They can look similar, and do a simliar job, to some degree, but they are not the same. It’s like comparing apple juice to orange juice. Both come from fruits, have similar properties but they certainly aren’t interchangeable. This is important because our infant’s digest breastmilk and formula differently, they contain different ingredients, and react differently in our infant’s GI tract.
Why do you want to mix?
Some very low birth weight infants (babies who are born weighing less than 3 lbs 4 oz) can benefit from fortified human milk which means adding a true fortifier NOT FORMULA to your expressed breastmilk, or donor milk, to increase proteins, lipids, zinc, vitamins, electrolytes, etc. This is not adding formula to breastmilk and this is also only recommended (if at all) to VLBW infants typically during their first tender days/weeks in the NICU setting. Read more on why human milk is fortified here.
Richard J. Schanler has a published article called Human Milk Supplementation For Preterm Infants in which he states, “A comparison of published studies of liquid preterm formula mixed with human milk and powdered human milk fortifier suggests that the liquid preparation resulted in a lower protein intake and net retention and lower intakes and retentions of calcium, phosphorus, and zinc. When sufficient human milk is unavailable, an alternative approach is to feed fortified human milk (using powdered fortifier) for as many feedings as there is milk available, then alternating with preterm formula for the remaining feedings.”
In summary, it has been found that some very low birth weight infants can benefit from mixing human milk fortifier (not formula) into expressed breastmilk but will be done so within the parameters of the NICU setting/Doctor supervison.
Why don’t we recommend?
The main reason we do NOT recommend mixing formula with human milk is because we are then altering the FDA approved make up of formula as well as the natural components in our breastmilk. 85% of our breastmilk is water, with the remaining 15% filled with fats, proteins and lactose. By altering the integrity of this we are exposing our infants to a higher concentration of water, effecting their likelihood of protein intake, and retentions of calcium.
Another reason is if our infant’s do not finish the prepared bottle of milk/formula it now all will go to waste. Once formula is activated it is only good for a few hours, where breastmilk can be good for days, weeks or months depending on storage options.
So with all that said, I will leave you with a few highlights;
Dr. Google is scary and should be avoided for important issues concerning our infant.
Feeding breastmilk is great, feeding formula is good, but let’s not combine them because google said you could.