The risks with sharing breast milk

Not all mothers have enough, or sometimes even any, breast milk. Unfortunately, this is more common among preemie moms – prematurity, stress, medications, and illness all affect supply.

Because the benefits of breast milk are so great, many moms are turning to other mothers who have an over abundant supply. They are hooking up via Twitter, Facebook, and blogs. “What’s the big deal?” many ask. After all, generations of the privileged were raised on wet nurses.

A study published in 2010 by Stanford researchers tells us the risks. The data comes from a milk bank, which is supplied by selfless mothers donating their milk. To donate milk, mothers must self-identify as low risk for infections (just like when you donate blood), but many are unfortunately not as low risk as they think. In fact, in this study 3.3% of donating moms were positive for one of six very serious infections: HIV, syphilis, hepatitis B, hepatitis C, human T cell lymphotropic virus type 1 (HTLV-1) and human T cell lymphotropic virus type 2 (HLTV-2).

Many women who offer up their milk say that they are screened or were tested in pregnancy, but in reality, even if they were, that was a year ago and screening for hepatitis C, HLTV-1, and HLTV-2 is not even performed during pregnancy (see ACOG guidelines).

What if they say they are low risk? Having worked in STD clinics most of my professional career, I can tell you women who get infected with these infections never, ever felt they were at risk (even those who had what I would definitely call high risk behavior, because no one ever thinks it is going to happen to them). And of course, many make assumptions that their partner is monogamous. When people give me a funny look about that one I just say two words: Tiger Woods. That kind of behavior is not limited to sports stars, not by a long shot.

What is even riskier is the mother who converts to HIV who supplying milk. In fact, the risk of transmitting HIV to a baby by breast milk in the first 90 days after she is infected with HIV is five times higher than if she were already HIV positive during pregnancy. That is why milk banks screen every sample for HIV (and the other infections). Milk bank donors also have to be a non smokers, be vaccinated against rubella and test negative for tuberculosis (TB). Milk banksĀ also pasteurize the milk to kill CMV (a virus found in up to 30% of the population that can be particularly harmful to a preemie) and HIV, although almost all of the nutritional properties stay intact.

Milk banks are run with the same precision as blood banks, hence the expense: $3.50-$4.50 an ounce (although ounce per ounce, donor milk is still a bit cheaper than blood). That is why affording milk bank milk is unreasonable unless covered by your insurance (often for a preemie in the NICU), or if you have the money of a celebrity, like Neil Patrick Harris).

So is donor milk safe? If it comes from a milk bank, absolutely. But otherwise, ask yourself if you would give your baby a blood transfusion from an unscreened donor? Most donors are motivated by altruism, but there is at least a 3.3% chance that milk from an acquaintance could do far more harm than good.

Would you give your baby donor milk from someone you met on line?

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10 Responses to The risks with sharing breast milk

  1. Heather says:

    We do use donor breast milk from a network of women I’ve gone to college or church with or their friends…I am grateful for it and my baby girl is thriving..we are in adoption process so it would have been challenging to breast feed b/c I’d have to take supplements & stimulate it. I think of it as communities used to do when women had low supply of milk (wet nurses) and we don’t just take it from any one…

  2. Sarah says:

    Yes, but only if I can have forms signed & a way to test and pasteurize the milk.

    I am in the process of donating my breast milk. I have been very shocked at how little information has been requested of me. I was expecting to sign a contract. I see it as the mother requesting the milk to offer me her expectations but instead she just asked to pick up my milk. This lack of questioning made me very skeptical and am now on the hunt of ways to protect myself and the babies who would get this milk. I wondered about wet nursing since my breast pump is creating more complications with keeping clean and comfortable. But I have found little on the risks of sharing breast-breast maybe because it isnt practiced as openly anymore?

  3. What about the fact that false positives ABOUND for initial blood screening tests? It is unacceptable that there is no mention of the (extensive) confirmatory testing required to get an actual, confirmed diagnosis (this is especially true for HTLV, but also for all other diseases that they tested for). The study’s authors did NOT disclose this very pertinent information, and simply stated that a blanket 3.3% of potential donor mothers had positive serology for infectious disease. That is not called ‘science’. It is called fear-mongering.
    It then comes as no surprise to see that one of the study’s authors is the recent past president of HMBANA (Human Milk Banking Association of North America). :/
    I do wonder… Why the divise? Why aren’t all advocates of human milk for human babies able to get on the same page? When posts like this come out, speaking to the supposed “inherent danger of other women’s breastmilk”, it makes me sick, thinking of the formula big-wigs sitting back, watching us play directly into their hands.
    Let me put it this way: I go to sleep far easier at night since the launch of Eats On Feets GLOBAL. Simply put, this is due to the fact that less powdered infant formula is finding its way into the unsuspecting guts of babies. I feel incredibly good about that.
    I must ask the author of this post how she sleeps at night, knowing that a disingenuous post such as this will inevitably scare mothers away from human milk –the optimal food for infants, the species-specific milk that human babies biologically expect to consume . . .

  4. Lisa says:

    Would I? Absolutely. Would I want to meet with them and/or get references from someone who knows them IRL? Yes.
    Also, anyone who can google can find the youtube video that shows you exactly how to flash heat breastmilk, destroying even HIV.
    (in case you can’t google,

  5. Mika says:

    So, 3.3% of lactating mothers have an infection transmittable disease? Or do 3.3% of donating mothers have these diseases? That would make for a lot of sick babies – even ones not getting donor milk, but milk from their mother who has HIV without her knowledge. Are we forgetting to worry about those babies?
    Also, yes, flash heating eliminates those risks. Risks are inherent to living, and if we are to speak of risks they must be weighed against other risks. What are the stats for serious complications due to formula? How many babies die of SIDS because they are formula fed? Do we have those actual numbers? In the case of preemies – NEC? Numbers please. Of course donor milk is getting bad press – no one (but babies) stand to profit. Money is at the heart of this very debate, and getting in the way of science. Let’s not forget that when deciding what is best and not be naive as to think that optimal health is at the core of this debate.

  6. Jennifer Gunter says:

    Thank you for your comment. However, increasing the rate of breastfeeding and access to breast milk is perhaps better achieved without vitriol.

    It is not fear-mongering to release the data on the % of infectious diseases that are present among women presenting as low risk donors to a milk bank. It is also not fear-mongering, but science to point out that the highest risk of transmitting HIV by breast milk is in the first 90 days post infection. These are simply facts.

    Blood transfusions are also life saving, but there are not many people who would accept a blood transfusion without knowing it has been tested for HIV/Hep B/Hep C etc.

    Just because breast milk is good for a baby does not mean that it is free of HIV or any other infection. As one donor has posted, she was shocked to find the woman accepting her milk asked for no information at all, which is shocking. And yes, while HIV can be inactivated by flash-heat, there is no published data on the efficacy of the home method for killing Hep C and Hep B.

    Some women may feel a 3.3% risk is low and others may feel a 3.3% risk is high, but without the data, they won’t be able to reach any valid conclusion at all. It would be nothing short of a lie to say that there is no risk of contracting an infectious disease by breast milk. In Africa, 40% of mother to infant transmission of HIV happens via breastfeeding.

  7. I assure you I am not bitter, nor am I out to criticise anyone needlessly. I was simply saddened by this post.
    I am concerned that there appears to be no difference for you between breastmilk and blood. Breastmilk is a food which passes through the digestive system; blood is not. Furthermore, breastmilk is not considered a biohazard, as human blood and other bodily fluids are. It is also important to note that an HIV-infected women does not necessarily have the virus present in her milk, whereas it is present in her blood. Yes, breastmilk is made from the mother’s blood, but most diseases are NOT inherent to breastmilk. Incidentally, the CDC advises women who are Hepatitis B and Hepatitis C positive to breastfeed their own infants. Blood banks, however, would not accept these mothers’ blood for donation. How do you, as a physician, explain this difference?
    You said “It is not fear-mongering to release the data on the % of infectious diseases that are present among women presenting as low risk donors to a milk bank.” What I am saying, is that this was NOT data based on confirmatory testing, and therefore does not present anything but an elevated and inaccurate percentage of women who are TRUE carriers of these diseases (due to the high rate of false positives which occur at the time of blood screening). In other words, the infectious diseases were NOT *confirmed* to be present among the potential donor women in this study, because blood screening does not offer the same accuracy as confirmatory testing.
    In Sub-Saharan Africa, it has been shown that for the babies who are born to HIV-infected mothers, and who are exclusively breastfed for 6 months, there is a 3-4% transmission rate (these are the babies who tested HIV-negative at the 6-wk mark). Interestingly, rates of transmission increase substantially if babies are mixed-fed (formula and breastmilk); this is because powdered infant formula and its forein milk proteins cause small tears to occur in the lining of the infant’s gut, effectively opening it up to pathogens. These studies, however, are problematic (as are the ones suggesting 40% of MTCT happens via breastmilk), because many of these babies may have, in fact, been infected by the virus at birth, and were simply not yet showing a seroconversion by 6 weeks of life (in other words, they weren’t actually infected by the breastfeeding/breastmilk).
    As for pasteurizing or flash-heating the milk at home, you are correct that the only virus to have been shown to be deactivated by this low-tech form of flash pasteurization, is HIV. However, I would like to encourage you to peruse another study from 2007, entitled “Antimicrobial and antiviral effect of high-temperature short-time (HTST) pasteurization applied to human milk” (the abstract for which is here:
    In this particular study, all lipid-encapsulated viruses and their markers (so, HIV, HTLV, Hepatitis B, Hepatitis C, CMV and EBV) were destroyed in a matter of a few seconds (3-4 seconds) upon reaching 72-degree temperature heat. We know that the average peak temperature that the milk reaches with the low-tech form of flash pasteurization (aka flash-heating) is 72.9 degrees. It is therefore no giant leap to suppose the same viral kill would occur with the flash-heating method. Further research is needed.
    And lastly, on the topic of not having monogamous partners, we are ALL at risk for this. I’d like to remind everyone to check themselves, as it is not only the potential donor women who have partners who sleep around on them. It could happen to *any one of us*, so I suppose I just get a sense of a moral high ground in such statements, which really ought to disappear. No one is immune. And therefore, everyone’s babies are at risk, and we should ALL be worried in this instance –for ALL babies!
    Once again, I am sorry to have come across as vitriolic. Not my intent. I am simply incredibly passionate about the health of mothers and babies, and about getting accurate information into the hands of those seeking it, in order for them to make informed milk sharing choices.

  8. I have to agree with Emma! While I’ve only (so far) received donor milk from my friend for my preemie, I am still actively searching on Eats on Feets for more milk for my son from other mothers. I’m smart, get copies of bloodwork & get to know the mother more personally before I receive any of her milk. I believe the risks of formula are worse than the potential risks that you suggested. And yes, some of the “facts” stated in this post are simply misinformation presented as truth. :o ( I hope you do not deter a mother from getting donor milk for her child by making her fearful of it.

  9. Jennifer Gunter says:

    The diagnosis of Hep B does not require confirmatory testing. It is a simply antigen screening test. It is is no way a difficult diagnosis. More testing is often done to help evaluate the expected course of the disease. Many families decline Hep B vaccination, and so babies are at risk. With Hep C , if the results indicate anti-HCV positive, then confirmatory testing is needed.

    The assertion that mixed BF supplemented by formula increases the risk of HIV transmission by a micro tears is not supported by scientific studies. Formula may affect mucosal IgA and other local defense mechanisms and this may be part of the explanation for higher rates of obesity and diabetes among formula fed infants, but this cannot be the sole mechanism to explain increased transmission of HIV with non exclusive breast feeding. This is because the rate of HIV transmission also increases when breast milk is supplemented with solids, not formula, at the age of 6 months. It seems that the act of non-exclusive breastfeeding and not the choice of supplemented food is the cause, because supplementing with formula or solids shares one common thing – a change in supply and demand. Some have hypothesized that that this could lead to milk stasis which may affect viral load, although the exact mechanism is not known.

  10. Carlie says:

    I am the proud mother of a 6 month old adopted baby girl. Due to the generosity and huge hearts of women out there, my baby has not had a drop of formula, and never will! As a mother and registered nurse, I feel that every baby deserves and wants the best start in life. This is done by starting the baby off on breast milk. I am grateful that my daughter has the BEST start and is thriving!! I believe that the risk is completely worth the BENEFITS of breast milk, and therefore I give my baby donated milk. I also pump myself a d give her what I can. I just think if more Dr and nurses adopted the thought that breast milk is best and that it can NEVER be replicated, more women would choose breast milk over formula feedings. Even if they cannot breast feed themselves, there are ways of still nourishing your child to the fullest!

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