The spread of HIV from mother to child has been cut in half in the United States over the past two years since doctors routinely began giving an AIDS-fighting drug to infected pregnant women.
The discovery that the drug AZT reduces AIDS transmission during childbirth has been one of the most important breakthroughs in the brief history of the epidemic.AZT immediately became standard treatment for HIV-infected pregnant women when this effect of the drug was learned in 1994.
At the 11th International Conference on AIDS meeting here this week, doctors from the U.S. Centers for Disease Control and Prevention showed the impact of this change on the spread of AIDS.
Dr. R.J. Simonds and others said that before AZT, 21 percent of children born to infected women caught the virus. Since then, this has dropped to 10 percent.
However, researchers hope they can do much better still, in part by developing better drug therapies and changing delivery practices.
"We feel we have the potential to reduce transmission to less than 2 percent, which has worldwide implications," said Dr. Yvonne J. Bryson of UCLA Childrens Hospital.
While AZT has substantially reduced mother-to-child spread of AIDS in industrialized countries, this form of transmission is relatively rare. About 6,000 HIV-infected women give birth in the United States annually.
Worldwide, about 3 million children are believed to have become infected during birth since the epidemic began, and more than 85 percent of them are in sub-Saharan Africa.
Despite AZT's potential to reduce this hazard, "the big problem is, for most women in the world infected with HIV, this is not a realistic option," said Dr. Peter Piot, head of the U.N.'s AIDS program.
Providing AZT costs $1,500 for each pregnancy, far too much for many poor countries. Furthermore, in many places, women don't seek prenatal care until it's too late to start on AZT.
As a result, the United Nations is starting a new study that will involve 1,900 HIV-infected women in South Africa, Tanzania and Uganda to see if less expensive strategies will work.