How can we best curb the risk of HIV transmission from an infected pregnant woman to her baby during pregnancy and breastfeeding while preserving the health of mother and child? The new study PROMISE, for “Promoting Maternal-Infant Survival Everywhere,” is addressing this question. Funded by The National Institutes of Health (NIH), the study, which will be conducted in as many as 18 countries, will enroll nearly 8,000 HIV-infected women who are pregnant or have recently given birth and don’t yet need HIV treatment, and nearly 6,000 HIV-exposed infants of these women.

The study has four components. First, it will examine which of two proven strategies is safer and more effective at preventing mother-to-child HIV transmission before and during delivery: beginning as early as 14 weeks of gestation, giving HIV-infected pregnant women either a three-antiretroviral-drug regimen or a regimen of zidovudine plus one dose of nevirapine during labor.

The second component of the study will compare the safety and efficacy of two methods of preventing mother-to-child HIV transmission during breastfeeding. The study team will randomly assign 4,650 mother-infant pairs either to receive a daily dose of infant nevirapine or to have the mothers take a three-antiretroviral-drug regimen throughout breastfeeding.

The study’s third component will examine the effects of a three-antiretroviral-drug regimen during pregnancy and breastfeeding to prevent mother-to-child HIV transmission on the health of HIV-infected mothers who don’t yet need treatment. Nearly 4,700 women will be randomly assigned either to stop the three-drug regimen after giving birth or weaning, or to continue the drug regimen indefinitely. The health of these two groups will be compared.

The last component of the PROMISE study involves protecting the health of HIV-exposed but uninfected infants. In resource-limited settings, it’s standard to give cotrimoxazole once daily to infants exposed to HIV at birth until the infants have stopped breastfeeding and are clearly HIV-uninfected. The study will determine whether continuing cotrimoxazole prophylaxis in HIV-exposed, uninfected infants from the end of breastfeeding through age 18 months cuts their risk of illness and death without causing side effects or generating bacterial resistance to cotrimoxizole.

The International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT)Exit Disclaimer network is conducting the PROMISE study with funds from the National Institute of Allergy and Infectious Diseases and the Eunice Kennedy Shriver National Institute of Child Health and Human Development, both of NIH.

For more information about the PROMISE study, visit: niaid.nih.gov/news/newsreleases/2010/PROMISE.htm.