SATURDAY, July 21, 2012 (HealthDay News) -- Babies born to HIV-positive women taking antiretroviral drugs to fight the disease may become exposed to the drugs in the womb and during breast-feeding, new research shows.
Hair and blood samples taken from the 3-month-old infants of women with HIV found evidence that two medications pass from mother to baby in the womb, while a third medication is passed both in utero and by breast milk.
The study by researchers from the University of California, San Francisco and Makerere University in Uganda included more than 100 HIV-positive mothers who were breast-feeding their infants and taking either lopinavir and ritonavir, or efavirenz.
HIV-positive women take antiretroviral drugs to help prevent them from spreading HIV to their fetus, but HIV-positive women are told not to breast-feed because HIV can be transmitted through breast milk, experts say. But in some developing nations, formula-feeding isn't an option.
The researchers analyzed hair and blood samples taken from the HIV-positive women and their 3-month-old HIV-negative infants.
Blood tests detect recent exposure to a drug, while hair samples show exposure over the course of a month. By sampling both the blood and hair of the infants, researchers said they were able to determine when the drugs were passed from the women to their babies.
"Since fetuses start growing hair in the womb, hair sampling gives us an opportunity to examine exposures to drug before birth," senior study author Dr. Monica Gandhi, associate professor of medicine at the UCSF Division of HIV/AIDS at San Francisco General Hospital and Trauma Center, said in a university news release.
The infants' hair samples revealed they had significant exposure to the antiretroviral drugs.
Based on the level of drug in the hair and in the blood, the researchers concluded that lopinavir and ritonavir exposure occurs in the womb but not during breast-feeding. Efavirenz appears to be transmitted in utero and during breast-feeding.
The findings could lead to the development of new ways to protect infants from HIV transmission and shed light on toxicities and resistance to anti-HIV drugs, the study authors noted.
"Our findings, as we verify them, will have important implications. One, being able to measure drug exposures of fetuses in the womb and during breast-feeding can help us understand how to better protect infants from HIV transmission from HIV-positive mothers during pregnancy, birth and after birth," said Gandhi. "Second, the development of resistance to antiretroviral medications in infants is an important issue," she added.
After low levels of exposure, HIV can develop resistance to the class of medications to which efavirenz belongs, she explained.
The study was expected to be presented on Saturday at the 4th International Workshop on HIV Pediatrics in Washington, D.C., ahead of a presentation at the 19th International AIDS Conference. The data and conclusions of research presented at medical meetings should be viewed as preliminary until published in a peer-reviewed journal.
The U.S. Centers for Disease Control and Prevention has more about mother-to-child HIV Transmission and Prevention.