• Posted October 29, 2025

Missing Nutrient Might Explain Health Problems Among Babies Born To Women With HIV

Babies born to women living with HIV often struggle with health problems and delayed development, even if they aren’t infected with the virus themselves.

The mothers’ breast milk might have something to do with it, a study published Oct. 28 in Nature Communications argues.

Breast milk in women with HIV contains significantly lower levels of the essential amino acid tryptophan, researchers found.

Tryptophan is important for an infant’s immune function, growth and brain development, and these low levels might explain the hardship faced by these babies, researchers said.

“What's particularly striking is that this metabolic signature persists even when mothers are on effective antiretroviral therapy,” lead researcher Dr. Nicole Tobin, a professor of pediatrics at UCLA’s David Geffen School of Medicine, said in a news release. “That helps explain why these children continue to need extra support despite advances in HIV treatment."

About 1.3 million children are born each year to women living with HIV, researchers said in background notes.

Antiretroviral therapy can prevent the virus from passing between mother and child, but in low-income countries these kids are still 50% more likely to die. They babies are also more likely to suffer infections and have delays in growth and cognitive development.

For the new study, researchers analyzed more than 1,400 breast milk samples from 326 women in Zambia, including 288 living with HIV.

Results showed that tryptophan concentrations were about 50% lower in the breast milk of women with HIV, compared to those not infected.

The women themselves also had lower tryptophan levels, suggesting that their bodies likely absorb the amino acid for their own use before it can be passed into breast milk.

Based on these results, future studies should investigate whether tryptophan supplements might help babies’ health, researchers said. The team plans to test this in animal models.

"We've known for years that children born to mothers living with HIV face greater health challenges, but we didn't fully understand why," senior researcher Dr. Grace Aldrovandi, chief of infectious diseases at UCLA's David Geffen School of Medicine, said in a news release. "This study reveals that tryptophan deficiency and altered metabolism may serve as a common denominator explaining the immune, growth and cognitive differences we see in these children.”

More information

The U.S. Department of Health and Human Services has more on preventing HIV transmission between mother and fetus.

SOURCE: UCLA, news release, Oct. 28, 2025