Study objective
A study by the Swiss Mother and Child HIV Cohort Study (MoCHiV) examined the extent to which HIV medications (antiretroviral therapy, ART) pass into breast milk and how much is absorbed by breastfed infants. Particular attention was paid to newer antiretroviral treatments, for which little data had previously been available.

Methodology
The study included 21 mother-child pairs. All the women were living with HIV, were on stable antiretroviral treatment, and had chosen to breastfeed. Analyses were carried out using blood samples from the mothers, breast milk, and – for some children – pediatric blood samples. The children were tested for HIV multiple times over an extended period.

Main results
The study shows that HIV medications pass into breast milk to varying degrees. The decisive factor, however, is this: the estimated amount of medication absorbed by infants through breastfeeding remained overall low and, for all substances studied, below a recognized safety threshold. No case of HIV transmission to the children was observed in the study group.

Interpretation and open questions
Despite this low overall drug exposure, variable concentrations were measured in children depending on the substances used. In the rare cases where HIV infection might nonetheless occur, this could theoretically increase the risk of developing resistance. The authors therefore emphasize the need for further research to better assess this residual risk.

Relevance for practice
This study supports the Swiss approach of allowing breastfeeding in the presence of HIV under strict conditions. The key elements are excellent treatment adherence, a durably suppressed viral load, and close medical monitoring of mother and child. Breastfeeding while living with HIV is thus possible – but it requires great discipline and clearly defined conditions.