Human Immunodeficiency Virus (HIV) can be passed from a mother to her infant during pregnancy, childbirth, or through breastfeeding. Significant scientific advancements have greatly reduced this risk. Understanding how this occurs and the available prevention methods is important for protecting infant health.
How Transmission Occurs
HIV is present in breast milk in cell-free and cell-associated forms. The mother’s viral load, the amount of HIV detectable in her bodily fluids, is the primary factor influencing transmission risk; higher loads increase risk.
Beyond viral load, other factors can also increase the risk. Damage to the infant’s gut lining from introducing other foods or liquids alongside breast milk can make the baby more susceptible to infection. Cracked nipples or mastitis in the mother can also increase HIV concentration in breast milk or expose the infant to maternal blood, further elevating transmission risk.
Preventing Transmission Through Medical Management
Antiretroviral Therapy (ART) for the mother is the most effective strategy for preventing HIV transmission during breastfeeding. ART reduces HIV in the mother’s body to very low or undetectable levels, substantially lowering transmission risk.
Consistent ART adherence throughout pregnancy, delivery, and breastfeeding is important for viral suppression. Even with an undetectable viral load, some virus may still be present in breast milk in very small quantities. Immediate infant ART after birth further reduces any potential risk. Studies show that with effective maternal ART, transmission risk can be less than 1%.
Infant Feeding Choices
For mothers with HIV, several safe infant feeding options exist. The choice often depends on individual circumstances and access to resources.
While “Undetectable = Untransmittable” (U=U) applies to sexual transmission, it does not fully apply to breastfeeding. A very small, non-zero risk remains even with an undetectable maternal viral load.
Exclusive formula feeding or pasteurized donor human milk eliminate transmission risk. If a mother on ART with a sustained undetectable viral load chooses to breastfeed, exclusive breastfeeding for the first six months is generally recommended over mixed feeding.
Mixed feeding involves giving both breast milk and other liquids or foods. This practice was historically associated with increased transmission risk without ART, potentially due to infant gut irritation.
Evolving Guidelines and Global Context
Guidelines regarding HIV and infant feeding have evolved significantly, influenced by effective ART. Early recommendations discouraged breastfeeding for mothers with HIV. However, evidence of ART’s effectiveness in reducing viral load and transmission risk led global health organizations to adapt recommendations.
Current recommendations vary based on healthcare resources and safe alternatives. Where safe water and formula are accessible, formula feeding may be advised as it carries zero transmission risk. Conversely, in low-resource settings lacking clean water and formula, breastfeeding with maternal ART is often recommended due to breast milk’s benefits and unsafe formula preparation risks. These evolving guidelines underscore the importance of individualized counseling and shared decision-making with healthcare professionals.