The antiretroviral drug nevirapine -- a low-cost medication that is used as a standard method of reducing mother-to-child HIV transmission in the developing world -- reduces the risk of vertical HIV transmission in repeat pregnancies, according to a study presented Wednesday at the 13th Conference on Retroviruses and Opportunistic Infections in Denver, the AP/Boston Herald reports. Nevirapine is given in pill form to HIV-positive women during labor to avoid vertical transmission and in syrup form to infants within 72 hours of birth. Michael Thigpen, an epidemiologist at CDC, and colleagues looked at 198 women who were treated in 2004 and 2005 with nevirapine at a hospital in Kampala, Uganda. Researchers found an HIV prevalence of 14.6% among infants born to women who had been treated with nevirapine during a previous pregnancy, compared with 17.6% for infants born to women who had not received the drug during a previous pregnancy. Thigpen said the findings contrast with earlier studies that suggest HIV might develop resistance to nevirapine after its first use, making the drug less useful in preventing vertical transmission in subsequent pregnancies. According to the AP/Herald, another study presented on Wednesday and conducted in South Africa and Cote d'Ivoire, finds results similar to the Ugandan study. Thigpen said, "Based on these findings, we believe nevirapine in repeat pregnancies remains an effective option in these resource-limited countries" (AP/Herald, 2/9).