HIV infection can be passed from a mother to her baby before or during birth and through breastfeeding.
Among HIV-infected pregnant women who have not received any preventive treatment, mother-to-infant HIV transmission (MIT) rates range from 15 to 25 percent in developed countries to 25 to 45 percent in developing countries, where an estimated 1,800 HIV-infected babies are born each day.
About 14 million women of childbearing age throughout the world are infected with HIV.
The highest rates of HIV infection among pregnant women have been reported in sub-Saharan Africa. In urban areas of southern Africa, for example, HIV rates of 20 percent to 30 percent among pregnant women are common, and rates greater than 40 percent have been recorded in some areas.
There are very few places outside sub-Saharan Africa in which the prevalence of HIV infection among pregnant women has reached 10 percent.
In 1994, a study sponsored by the National Institutes of Health demonstrated that the drug AZT reduced the risk of MIT by two-thirds, from 25 percent to 8 percent. In the study, known as ACTG 076, AZT therapy was initiated in the second or third trimester and continued during labor, and infants were treated for six weeks following birth.
The ACTG 076 regimen, now standard in the United States, is too expensive and impractical for widespread use in developing countries, where many women may not receive prenatal care.
The nevaripine regimen used in the study reported in the current issue of The Lancet is 200 times cheaper than the ACTG 076 AZT regimen. For this reason, the finding brings hope that an affordable alternative may be on the horizon.