For mothers living with HIV, one of the biggest worries is passing the virus to their baby. A large study from Tanzania, led by researchers at Karolinska Institutet in Sweden, shows that with modern antiviral treatment, that risk can be brought very low, even in a lower-income country with high rates of HIV.
How HIV can pass from mother to child
Without treatment, HIV can be passed to a baby during pregnancy, during birth or through breastfeeding. Antiretroviral therapy (ART), the combination of medicines used to treat HIV, lowers the amount of virus in the body. When the virus is kept at very low or undetectable levels, the chance of passing it on drops dramatically.
Earlier estimates from UNAIDS suggested that in Tanzania, about 11% of babies born to mothers with HIV became infected. Whether modern treatment could match the very low transmission rates seen in wealthier countries had not been clearly shown in large studies from high-burden African settings.
How the study worked
Researchers followed more than 13,000 pregnant women living with HIV who received antiretroviral treatment as part of routine maternity care in Dar es Salaam, Tanzania, between 2015 and 2017. Their babies were followed for 18 months after birth, a point by which most mothers had stopped breastfeeding. The study was published in The Lancet HIV.
What the researchers found
- Overall transmission was low. About 1.4% of babies acquired HIV, far below earlier estimates.
- Starting treatment early made a big difference. Among women who were already on treatment when they became pregnant, the risk was about 0.9%.
- Late treatment raised the risk. The risk more than doubled for women who started treatment late in pregnancy or who had advanced HIV.
It was one of the largest studies from Africa to follow babies through the end of the breastfeeding period.
Because the women in the study were treated through ordinary clinics, the results reflect what is possible in everyday care.
Why it matters
The results support the World Health Organization’s goal of eliminating mother-to-child transmission of HIV. They show that routine, widely available treatment can protect babies in real-world settings, not just in research trials. The researchers stressed that the remaining gaps can be closed by diagnosing HIV earlier, starting treatment before or early in pregnancy, and offering more support to young mothers.
What this means for you
- Get tested. HIV testing is recommended as a routine part of prenatal care. Knowing your status early gives your baby the best protection.
- Start and stay on treatment. If you’re living with HIV, taking antiretroviral therapy every day keeps the virus under control and protects your baby. Ideally, start before pregnancy.
- Talk to your care team about feeding. Guidance on breastfeeding varies by country and situation. Discuss the safest option for you and your baby.
- Make sure your baby is tested. Babies born to mothers with HIV need testing and sometimes preventive medicine after birth.
- Partners can help too. Testing for partners and, where appropriate, preventive medicine (PrEP) for HIV-negative partners lowers the risk of new infections during pregnancy.
The bottom line
A study of more than 13,000 mothers in Tanzania found that antiretroviral treatment cut the risk of passing HIV to babies to about 1%, and even lower when treatment started before pregnancy. Early testing and treatment are key to protecting the next generation.
This article is for general information and isn’t medical advice. Talk with your healthcare provider about your individual needs.
