How science is transforming one of healthcare's most complex dilemmas
For mothers living with HIV-1, one of the most personal and consequential decisions they face is how to feed their newborn. This choice represents a profound dilemma: breast milk provides ideal nutrition and vital immune protection for infants, yet can also transmit the very virus that threatens their health. For decades, the medical community responded with a simple, uniform directive—avoid breastfeeding entirely. But as scientific understanding has deepened, that clear boundary has blurred, revealing a more nuanced reality where careful management can potentially allow mothers living with HIV to safely breastfeed their children.
The evolution of this guidance represents one of the most compelling stories in modern medicine, intertwining virological breakthroughs, transformative drug therapies, and a growing recognition of patient autonomy. This article explores the science, research advances, and policy shifts that are reshaping how we approach HIV-1 and breastfeeding—a journey from blanket prohibitions to personalized risk assessment that honors both clinical evidence and human dignity.
HIV-1, the most common strain of the human immunodeficiency virus, attacks the body's immune system and can be transmitted through certain body fluids, including breast milk 1 . The virus exists in breast milk as both free-floating viral particles (HIV-1 RNA) and as virus-infected cells (HIV-1 DNA), both of which can potentially lead to infection in the breastfeeding infant .
Without intervention, rates of vertical transmission (the term for mother-to-child transmission) of HIV-1 during pregnancy, labour, delivery, and breastfeeding range from 15% to 45% 5 . However, this alarming statistic belies a more complex reality—multiple factors influence transmission risk, creating opportunities for intervention.
The single most important factor in preventing HIV transmission through breastfeeding is maintaining an undetectable viral load through consistent antiretroviral therapy (ART) 5 . ART works by suppressing viral replication, reducing the amount of HIV in bodily fluids including breast milk to very low or undetectable levels.
For mothers on ART with a sustained undetectable HIV viral load during and after pregnancy, the risk of transmission through breastfeeding falls to less than 1%, though it's crucial to note the risk is not zero 1 .
Intriguingly, research has revealed that how a mother feeds her infant affects viral concentrations in breast milk. A landmark study in Zambia found that:
Associated with lower HIV-1 concentrations in breast milk
Linked to significantly higher viral levels
Highest viral concentrations occurred when breastfeeding stopped abruptly
This explains a puzzling earlier finding—that early weaning didn't reduce HIV transmission as much as models predicted. The act of weaning itself temporarily increases viral concentrations in breast milk, potentially elevating transmission risk during this transition period.
While ART has transformed HIV management, it requires consistent daily dosing that presents challenges in resource-limited settings. Seeking alternatives, scientists have pioneered innovative approaches including gene therapy to provide long-lasting protection.
In a groundbreaking 2024 animal study led by Dr. Mauricio Martins at The Herbert Wertheim UF Scripps Institute, researchers administered a single injection of gene therapy to newborn macaques 2 . The therapy used a harmless adeno-associated virus as a delivery vehicle containing genetic instructions for the body to produce 3BNC117, a "broadly neutralizing antibody" capable of blocking a wide variety of HIV strains 2 .
| Age at Administration | Therapy Success Rate | Protection Against Oral HIV Challenge | Duration of Protection |
|---|---|---|---|
| At birth | ~90% | Nearly 100% | Several years (into adolescence) |
| Older infants | Decreased rate | Not reported | Not reported |
The implications are profound—this one-time intervention could potentially provide multi-year protection against HIV transmission during breastfeeding, particularly valuable in regions with limited healthcare resources where daily ART adherence proves challenging 2 .
As more mothers with HIV choose to breastfeed while on ART, questions have emerged about drug transfer to infants through breast milk. A 2025 study published in Scientific Reports addressed this concern by monitoring ART drug levels in breastfed HIV-exposed uninfected (HEU) infants 8 .
The researchers calculated the Relative Infant Dose (RID), with a target of below 10% indicating low risk of adverse drug reactions. Their findings revealed substantial variability:
| Drug Class | Drug Name | Relative Infant Dose (RID) Findings | Clinical Implications |
|---|---|---|---|
| NNRTIs | Rilpivirine | As high as 633% in one infant | Potential for drug accumulation |
| NNRTIs | Nevirapine | Up to 180% | Requires monitoring |
| Integrase Inhibitors | Dolutegravir | Up to 240% in one infant | Variable transfer |
| Integrase Inhibitors | Raltegravir | Below detectable levels | Favorable safety profile |
| Protease Inhibitors | Darunavir | Below detectable levels | Favorable safety profile |
Despite these variable drug levels, researchers found no consistent pattern between elevated ART levels and neutropenia (low neutrophil count), a potential side effect 8 . This suggests that while monitoring may be prudent, drug transfer doesn't consistently cause this hematological abnormality.
Medical interventions alone cannot address the full complexity of HIV and breastfeeding. A 2025 systematic review and meta-analysis of randomized controlled trials evaluated non-pharmacological interventions to support breastfeeding among people living with HIV 6 . The analysis found that:
Associated with a borderline increase in maternal viral suppression
Pooled interventions improved exclusive breastfeeding uptake by 38%
The certainty of evidence was low to very low, highlighting the need for more robust studies.
The World Health Organization (WHO) has significantly revised its stance on HIV and breastfeeding over time. In 2016, WHO began advising that in countries that have opted to promote and support breastfeeding together with ART, mothers living with HIV who are on ART and adherent to therapy should:
Breastfeed exclusively for the first 6 months
Add complementary feeding until 12 months of age
This marked a dramatic shift from previous advice to stop breastfeeding at 12 months if a safe alternative could be provided.
While global guidelines have evolved, implementation at national levels has been uneven:
| Country/Region | Policy Approach | Key Features | Recent Changes |
|---|---|---|---|
| United States | Shared decision-making | Evidence-based counseling; emphasis on viral suppression | Reversed formal prohibition in 2023 4 |
| Canada & Europe | Case-by-case approach | Support breastfeeding with undetectable viral load | Several countries now permit with monitoring 4 |
| Latin America | Mostly restrictive | Widespread prohibition persists | Argentina, Trinidad, and Tobago beginning updates 4 |
| Sub-Saharan Africa | Context-specific | Balance ART benefits with breastfeeding protection | Alignment with WHO guidelines where resources allow 2 |
The policy discussion increasingly recognizes breastfeeding as not just a public health issue, but a human right. As Rafael Pérez-Escamilla, PhD, of Yale University notes:
"It is not justifiable that outdated recommendations continue to deny support to women with HIV who want to breastfeed" 4 .
This perspective acknowledges that reproductive rights include feeding choices, and that equitable care requires supporting these decisions with appropriate medical infrastructure.
Studying HIV-1 transmission through breastfeeding requires specialized tools and approaches. Here are some essential components of the research toolkit:
Gene delivery vehicles used to transport protective antibody genes into cells; valued for their safety profile and stability in non-cold chain conditions 2
Specialized antibodies that can block a wide variety of HIV strains; examples include 3BNC117 used in the gene therapy study 2
Laboratory techniques to measure both free-floating virus (RNA) and cell-associated virus (DNA) in breast milk; crucial for understanding transmission dynamics
Pharmacological method for assessing infant drug exposure through breastfeeding; calculated by dividing infant drug level by maternal drug level 8
Animal research approach using primate equivalents of HIV administered orally to simulate breastfeeding transmission; enables controlled prevention studies 2
Analytical technique for measuring antiretroviral drug concentrations in biological samples like serum and breast milk 8
The journey of understanding HIV-1 and breastfeeding reveals a broader truth in medicine: as science advances, seemingly simple prohibitions often give way to more nuanced approaches that balance risks and benefits while respecting individual choice. What began as a uniform directive to avoid breastfeeding has evolved into a sophisticated strategy combining antiretroviral therapy, viral load monitoring, and shared decision-making.
Yet the trajectory offers hope. From the once-unimaginable concept that mothers with HIV could safely breastfeed, to the frontier of gene therapies that might one day provide long-lasting protection 2 , the field continues to advance. Each development brings us closer to the ultimate goal: an HIV-free generation where every child can benefit from the profound nutritional and immunological advantages of breastfeeding, regardless of their mother's HIV status.
The story of HIV-1 and breastfeeding continues to be written—not just in laboratories and policy documents, but in the lived experiences of mothers and infants worldwide who navigate these complex choices in pursuit of health and connection.