We're feeding our 3-month-old a combination of breastmilk and formula. The ratio is about half and half.

Are we still getting the benefits of breastmilk? I ask because when I read about the benefits of breastmilk, it seems the studies are only on babies who are fed breastmilk exclusively. Are we still getting benefits even if it's not exclusive?

We can't feed breastmilk exclusively.

  • According to a study I read (and can't find, thus comment not answer)certain allergies are less likely to occur when the mother breastfeeds and doesn't have the same allergies. The effect does not apply to all allergies. The effect was significantly reduced for mothers who partially breastfed. Unfortunately, most studies regarding allergies and breastfeeding are flawed in multiple ways (mostly because studies can't just lock up the mother and baby in a lab for a few years), so most of the data we have about breastfeeding is just educated guesses.
    – Peter
    Aug 6, 2017 at 12:15
  • 1
    It would help if you laid out exactly what benefits you thought you were getting. This large study of discordant siblings found no significant differences in health measures between breastfed and non-breastfed siblings. ncbi.nlm.nih.gov/pmc/articles/PMC4077166. The PROBIT studies in Belarus didn't find much either. A recent study in North Ireland of cognitive and behavioral development found nothing eithrr, (pediatrics.aappublications.org/content/early/2017/03/23/…) so what benefits exactly were you expecting?
    – swbarnes2
    Aug 7, 2017 at 18:43

1 Answer 1


You are asking an incredibly broad question when you say "benefits".

There are a number of things that can be beneficial in breastfeeding, for the baby and the mother. So how much of a benefit will be obtained varies depending on what you are looking for here. Also, keep in mind that any "reduction" of risks, etc based on breastfeeding is only that. You can breastfeed 10 kids and one is very healthy, the next not so much, another has some issue breastmilk is said to reduce, you have issues maybe that were supposed to be offset by breastfeeding. At the end of the day, my point is, we all have to be realistic that there are statistical findings that are clinically significant but that doesn't mean we can truly prevent all things by breastfeeding. Likewise, if we cannot breastfeed exclusively, that doesn't inherently mean it has no value. If nothing else, it is safe, nutritious, incredibly portable when you are on the go & nearly free, so there is always that.

There are always antibodies in breastmilk, whether you give the baby one ounce a day or 25 ounces. Lactation in & of itself has been found to have potential medical benefits to women (such as lowering uterine cancer, possible breast cancer, etc).

I tend to look at such questions in life this way. Let's say ideally you want to walk 5 miles a day for health, but you are really only able to walk 2-3 times a week. Would it still be worthwhile those 2-3x times or no? What if it were only once a week?

The great news in life is that anything that is good for us is nearly never all or nothing. Usually you can find a way to balance it with what feels doable.

And as far as what exact benefits there are when feeding half & half, I do not think anyone being intellectually honest could tell you specifically what you do get in that ratio, but I can tell you it must make some difference, as I can link you to a study abstract that shows that breastfed infants (and it includes partially breastfed) show a larger thymic index & the thymus is critical in immune system development. https://www.ncbi.nlm.nih.gov/pubmed/8888912

  • You need to cite the paper that actually shows a difference in immune function, that shows children getting sick less (preferable long after weaning), not pointing to a random measurement and saying "see, that must mean a clinical difference!". If this is the best you can do, you've shown nothing relevant.
    – swbarnes2
    Aug 7, 2017 at 18:37
  • You would need a membership to view more than the abstract. I am not sure how useful it would be to link to something that average person won't get to access.
    – threetimes
    Aug 8, 2017 at 8:09

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