In the new research study, HIV-positive pregnant women in Nairobi, Kenya, were randomly assigned to one of two treatments to prevent HIV transmission to their infant.
One group received the standard treatment for poor countries: treatment of the mother with the antiviral drug zidovudine starting six weeks before delivery, plus a single dose of the drug nevirapine for the infant after birth (ZDV/sdNVP).
Another group received a three-drug HAART combination.
This "triple therapy" combination-the standard treatment for HIV-infected pregnant women in wealthier countries-also started six weeks before delivery. HAART then continued for six months after birth, with the goal of preventing HIV transmission during breast-feeding.
The two groups were compared for measures of HIV resistance to antiretroviral drugs.
Three months after treatment, sophisticated gene studies found that HAART reduced drug resistance, though did not eliminate it completely. Low levels of resistant virus were detected in 75 percent of women receiving ZDV/sdNVP, compared to just 18 percent of those receiving HAART.
The study "provides strong evidence that short-course HAART results in lower rates of antiretroviral resistance compared with the standard ZDV/sdNVP regimen," according to the researchers.