Breastfeeding With an Undetectable Viral Load: What Do We Know?

I'm not a mother and sometimes I think that when it comes to breastfeeding I should just keep my big trap shut.

I have started and stopped this blog so many times. But I've decided to write it and here's why.

I don't think women are given enough information about breastfeeding. And I don't think their choices are respected enough. I believe that women should be empowered to make their own choices about breastfeeding and they should be supported -- not policed -- in these decisions.

I also believe that women living with HIV are not often given sufficient information about the risks associated with breastfeeding. I'm seeing some voices emerge from the U=U community in support of the idea that U=U applies to breastfeeding. It doesn't. And failing to look directly at the risks, examine them, and provide a balanced look at the issue is not supportive.

Supporting women to make informed choices on the topic does not mean eliminating information on either side of the argument. It means respecting women's ability to understand scientific information and sharing that information willingly -- instead of just telling them what not to do. And it means supporting women to make choices even when these choices may include small risks.

In this blog post I will explain why the risks are there but also why I believe that women should be supported in making a choice to breastfeed, and why I believe that more information for women is key.

Why Do We Hear Mixed Messages About HIV and Breastfeeding?

Many HIV+ women I talk to about the topic of breastfeeding express confusion why the guidelines on breastfeeding vary from country to country. Women from Africa or other parts of the world will be encouraged to breastfeed despite their HIV status. From the perspective of an HIV+ woman, why should they be encouraged to breastfeed in Rwanda but not in the UK or Canada?

The answer is that in low-resource settings, where infants may be at higher risk from infant mortality caused by diarrhoea or illnesses related to parasites that may enter the body through foreign substances (unclean water or formula), breastfeeding is the best choice. When weighing the risks and benefits, breastfeeding is the safer choice.

A different approach will be taken in high resource settings where the risks and benefits are also weighed. In the UK or Canada for instance, where there is clean drinking water and formula available, it is a safer choice to simply eliminate the risk of transmission through breastfeeding. In these countries, the risk of HIV transmission outweighs any other risks. Of course, what makes sense from a public health perspective is not always what makes sense for the individual. But I'll get back to that.

Does Undetectable = Untransmittable Apply to Breastfeeding?

More and more women are wondering about the role of an undetectable viral load. It seems to be pretty clear than an undetectable viral load does significantly lower the risk of transmission through breastfeeding. It lowers this risk by about 60%. This means that the risk is indeed low! But it is not zero.

When it comes to sexual transmission, we have a good body of evidence that proves that people living with HIV who have a sustained undetectable viral load do not transmit HIV to their partners, even through otherwise unprotected vaginal or anal sex. There has never been a case of sexual transmission from a person with an undetectable viral load. This is why we can unequivocally state, with sexual transmission, Undetectable = Untransmittable. There is no risk, or for the overly cautious, we could at most say there is a negligible one.

Unfortunately, we cannot say this about breastfeeding.

For one thing, there have been documented cases of transmission through breastfeeding when the mother had an undetectable viral load. Two studies showed that in 15% of cases where HIV was transmitted to infants through breastmilk, the mother was undetectable. So while PARTNER revealed zero transmissions, we simply cannot use the same terminology here given that transmissions through breastfeeding have taken place.

But Why Can Infection Occur Through Breastfeeding When It Can't Through Sex?

There are a few reasons why breastfeeding poses a risk while sexual transmission does not. One reason is that cell-associated virus is responsible for many or most infections through breastfeeding. This is a significant point as viral load testing does not measure cell-associated virus. And, because transmission takes place in an infant's gut, there are lots of other immune cells that play a role in transmission, which would not be the case in sexual transmission.

Latently infected resting cells, HIV-infected macrophages and lymphocytes, and HIV RNA have all been found in breastmilk from women on treatment and play a role in infection. For example, macrophages and lymphocytes (white blood cells which play a role in the immune system) also facilitate the infection of CD4 cells by helping to transport HIV across the epithelial barriers.

Other reasons for increased risk include that breastmilk contains a lot of CD4 cells; infants are exposed to up to 1 million CD4 cells per day. This allows easy access to CD4 cells for infection. Inflammation caused by, for example, mastitis, breast abscesses, and engorgement, also increase the risk and other sources of infection such as cracked, blistered nipples can also provide another source of infection.

The process of infection through the infant's gut from breastfeeding is thus quite different from that of sex, not to mention the added risk that comes from the volume of fluid that is ingested! Compared to sexual transmission, there is considerably more exposure to an infant who is guzzling breastmilk day and night for months on end, compared to even the lengthiest chem sex party!

This, and the evidence of transmission, has led researchers to conclude that "Indeed, the equation 'no detectable HIV-1 RNA equals no transmission,' which correctly applies to sexual transmission and perinatal transmission of, does not apply to breast-feeding transmission." (Van de Perre, P., Rubbo, P-A., Viljoen, J., Nagot, N., Tylleskär, T., Lepage, P., Vendrell, J-P., Tuaillon, E. , 2012).

Women Should Be Empowered to Make an Informed Choice

I believe it is unfair of us to incorrectly state that U=U when it comes to breastfeeding. We are giving women misinformation by doing that. We are not supporting them in understanding the scientific information so that they -- for themselves -- can weigh the risks and benefits.

Mothers do not have it easy. They face a tonne of pressure and criticism from outside voices, be they scientific, medical, social, cultural, or familial. The same applies to many facets of motherhood, including breastfeeding.

The message that "breast is best" is so heavy handed that it makes it difficult to for mothers to feel anything other than a terrible mother for failing to give their child "the best". Pressures can come both internally and externally -- there are cultural expectations, norms and beliefs; emotional and physiological desire, information on the internet, feelings of loss, grief, and guilt, the desire to bond with the baby, the opinions of friends and family, pressure from health and social care organisations, the social construction of motherhood and identity, concern for the baby's health ... and good old HIV stigma. Stigma, both external and internal. Stigma, that can, particularly for women in high prevalence communities, lead to gossip or even inadvertent disclosure of HIV status -- which comes with a genuine threat to health and wellbeing.

Still, lots of women will choose to sacrifice everything for their baby, and upon knowing the risks, may choose not to breastfeed.

This is part of making an informed choice, however. It should be up to the woman to weigh the risks and benefits -- but that necessitates a proper explanation of the risks and why they exist.

Women with HIV who are considering breastfeeding should be given scientific information about how transmission occurs and the role of the immune system -- not just cursory information. I believe that everyone has the capacity to understand scientific information about HIV transmission if it is presented in a clear and thoughtful manner. But how often do we have opportunities to communicate with health practitioners about this?

More often than not, we are simply told not to do something. We are not told how, or why, a risk is present. Only that it's there.

Supported to Breastfeed Despite the Risks

Here in the UK, women with HIV in the UK are advised not breastfeed their babies even with an undetectable viral load. The British HIV Association (BHIVA) and Children's HIV Association (CHIVA) Position Statement on Infant Feeding in the UK (2010) states:

To prevent the transmission of HIV infection during the postpartum period, BHIVA/CHIVA continue to recommend the complete avoidance of breastfeeding for infants born to HIV-infected mothers, regardless of maternal disease status, viral load or treatment.

However, in the UK, breastfeeding is not an automatic child protection issue and mothers who breastfeed will still receive support. In Canada, (which also has harsher criminalisation laws), a more hard-line approach is used. I think that the British model is much better.

Even With All of the Risks I Have Described, I Still Think That Women Should Be Able to Make the Choice to Breastfeed


  1. While it's clear that being undetectable does not eliminate the risk of infection as it does in sexual or vertical transmission, it significantly reduces the risk. The risk is low enough that, in my opinion, women should have the option to take this risk.
  2. Women should have the right to make the best decisions about the health of their children. We should have the ability to weigh the risks and benefits and decide for ourselves what is the best decision given the context of our lives. But this means that we should be given more, not less information. I think that HIV+ women should be given more information on the topic -- including why the guidelines are different by country, the rates of transmission, and how infection occurs.
  3. Public health decisions are made from a population health perspective, not an individual one. In this case, guidelines are set because the absolute safest thing to do is not to breastfeed. If no mothers living with HIV will breastfeed, we eliminate that risk altogether. If we take our goal of eliminating HIV transmission, this does make sense. But many times this translates to advice that just does not suit the context of our individual lives. As Harvey Pekar wrote, "ordinary life is pretty complex stuff." For many reasons, we simply cannot always make the safest, or the most optimal choice that is given under advisement of our doctors.
  4. In situations where women feel that abstaining from breastfeeding is not possible or simply not the right choice, it's far better to support women to reduce the risks, such as by providing strategies that can help to lower risk (such as medication adherence, exclusive breastfeeding, avoiding breastfeeding if there is an infection or cracked, blistered nipples, etc.)

Writing this piece may alienate me from either side of the argument. But I am concerned that women may not necessarily have the information nor the support from the medical communities on this subject, nor from wider health and social care or even from HIV/AIDS organisations. The HIV community has an important role to play in listening, training, supporting and advocating on this issue.

Works Consulted

Breastfeeding and HIV International Transmission Study Group, Coutsoudis A, Dabis F, Fawzi W, Gaillard P, Haverkamp G, Harris DR, Jackson JB, Leroy V, Meda N, Msellati P, Newell ML, Nsuati R, Read JS, Wiktor S. Late postnatal transmission of HIV-1 in breast-fed children: an individual patient data meta-analysis. J Infect Dis. 2004 Jun 15;189(12):2154-66. Epub 2004 May 26.

British HIV Association (BHIVA) and Children's HIV Association (CHIVA) Position Statement on Infant Feeding in the UK (2010)

Canadian Paediatric Society (2017). Testing for HIV infection in pregnancy.

Coovadia HM1, Rollins NC, Bland RM, Little K, Coutsoudis A, Bennish ML, Newell ML. Mother-to-child transmission of HIV-1 infection during exclusive breastfeeding in the first 6 months of life: an intervention cohort study. Lancet. 2007 Mar 31;369(9567):1107-16.

Government of Canada (2015). Nutrition for Healthy Term Infants: Recommendations from Birth to Six Months. A joint statement of Health Canada, Canadian Paediatric Society, Dietitians of Canada, and Breastfeeding Committee for Canada

Gordon, B. Breastfeeding wars: is breast really best? To breastfeed or not to breastfeed? If you feed your baby formula rather than mother's milk, you've probably already felt the disapproval of the "Breastapo". But is breast really always best? The Telegraph 1:20PM BST 20 Aug 2014.

HIV iBase (2015), Guide to HIV, Pregnancy & Women's Health.

Kennedy, L., Serghides, L., Greene, S. Webinar: A Complicated Dilemma: HIV and infant feeding (2014).

Khosla, P., Ion, A., & Greene, S. (2016). Supporting Mothers in Ways that Work: A Resource Toolkit for Service Providers Working with Mothers Living with HIV. Hamilton, ON: The HIV Mothering Study Team.

Manigart O1, Crepin M, Leroy V, Meda N, Valea D, Janoff EN, Rouet F, Dequae-Merchadoux L, Dabis F, Rouzioux C, Van de Perre P; Diminution de la Transmission Mere-Enfant Study Group. Effect of perinatal zidovudine prophylaxis on the evolution of cell-free HIV-1 RNA in breast milk and on postnatal transmission. J Infect Dis. 2004 Oct 15;190(8):1422-8. Epub 2004 Sep 9.

O. Manigart, M. Crepin, V. Leroy, N. Meda, D. Valea, E. N. Janoff, F. Rouet, L. Dequae Merchadoux, F. Dabis, C. Rouzioux, P. Van de Perre; Diminution de la Transmission Mere-Enfant Study Group, Effect of perinatal zidovudine prophylaxis on the evolution of cell-free HIV-1 RNA in breast milk and on postnatal transmission. J Infect Dis. 190,1422-1428 (2004).

Overbaugh, J., and Milligan, C. (2014, December 14). The Role of Cell-Associated Virus in Mother-to-Child HIV Transmission. J Infect Dis. 210 (suppl 3).

Public Health England (2015). HIV in the UK -- Situation Report 2015.

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Royal College of Nursing. (2016). Formula feeds: RCN guidance for nurses caring for infants and mothers.

UNICEF UK (2012). Guide to the Baby Friendly Initiative Standards.

Van de Perre, P., Rubbo, P-A., Viljoen, J., Nagot, N., Tylleskär, T., Lepage, P., Vendrell, J-P., Tuaillon, E. (2012). HIV-1 Reservoirs in Breast Milk and Challenges to Elimination of Breast-Feeding Transmission of HIV. Science Translational Medicine. 118 July Vo 4, Iss.143.

World Health Organization. (2016). Guideline: updates on HIV and infant feeding: the duration of breastfeeding, and support from health services to improve feeding practices among mothers living with HIV.

World Health Organization. HIV/AIDS: Mother-to-child transmission of HIV.