The use of antiretroviral drugs—used to halt the progression of HIV—during pregnancy does not appear to predispose infants to birth defects, contrary to popular belief about the harmful effects of the medications, a School of Public Health study found.

According to Paige L. Williams, senior lecturer on biostatistics at the School of Public Health who piloted the research team, pregnant women infected with HIV are recommended to take HIV drugs. Though such medications have proven largely safe to use, particular types have been associated with increased rates of birth defects, Williams said.

The recent study examined the incidence of negative health effects in infants whose mothers used antiretrovirals and was designed to help doctors assemble the safest combination of HIV drugs by indicating which are associated with the least risk.

With more than 3,000 HIV-infected mothers and their children enrolled in the ongoing study taking place at multiple institutions, the drugs have so far proved to be largely benign in terms of birth defects, Williams said.

“The findings from this study are generally reassuring, and suggest that most antiretrovirals are unlikely to cause an excess in congenital abnormalities when used in the first trimester,” said Roger L. Shapiro, associate professor in medicine at Harvard Medical School and the School of Public Health.

Despite these initial results, Shapiro expressed concern over the onsent of birth defects in infants in later years, which could correspond to mothers’ use of antiretroviral drugs during pregnancy.

According to Shapiro, more data must be gathered to determine whether Atazanavir, a drug recommended by U.S. guidelines for pregnant HIV-positive women, actually causes harmful effects on infants in the later years. Another agent of concern is Efavirenz, which has been previously linked to neural tube defects.

“The high overall prevalence of congenital abnormalities in this study, especially in later years, is of some concern,” he said. “Further studies will be needed to monitor for increasing prevalence over time.”

Williams attributed the motivation for this study to Lynn. M. Mofenson of the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

“She felt very strongly that we have an ethical mandate to ensure that mothers have safe drugs,” Williams said.