Mother and Child--The HIV Connection
by Marian Segal
According to the Surgeon General's 1993 report on HIV infection and AIDS, about 1 in 4 of babies born to HIV-infected women at that time became infected before or during birth. Scientists have been trying for some time to discover what influences whether or not a child will be affected.
No one is certain when viral transmission occurs. Possibilities include: during childbirth, from exposure to maternal blood or vaginal fluids; or earlier in pregnancy, when there may be a mixing of blood or passage of the virus across the placental wall.
In August 1994, FDA approved Retrovir (zidovudine, or AZT) for use in preventing transmission of HIV from infected pregnant women to their babies. Approval was based on results of a federally sponsored study showing that the risk of transmission to newborns from infected mothers is significantly reduced in women receiving zidovudine during pregnancy. Since its approval, AZT has been observed to reduce HIV transmission to infants from 25 percent in untreated mothers to 8 percent in those treated with AZT.
In response to reports of a study suggesting that very high daily doses of AZT increased certain types of cancer in baby mice, an independent NIH advisory panel unanimously agreed in January 1997 that the benefits of HIV-infected pregnant women taking AZT outweigh the theoretical concerns raised by the study. There are no reports of any human child developing cancer after AZT treatment and it is unclear whether the mouse study results apply to humans. The committee also recommended that pregnant HIV-infected women be told about the study before being given the drug and emphasized the need for careful long-term follow-up of all children born to pregnant women who received AZT.
To gain the most benefit from AZT therapy, women need to be diagnosed early in the course of their infection and before or early in the pregnancy. To this end, the Public Health Service recommended HIV counseling and voluntary testing of all pregnant women in the United States.
Apart from the timing of transmission, studies suggest that the likelihood of the child becoming infected may correlate with the mother's health during the pregnancy or birth. In the June 9, 1993, Journal of the American Medical Association, Michael E. St. Louis, M.D., and his colleagues reported that a baby is more likely to become infected if the mother is in the very earliest stage of infection (when the virus is thought to be abundant) or in an advanced stage of disease, or if the membrane surrounding the placenta is inflamed.
A child can also become infected after birth through breast-feeding. The national Centers for Disease Control and Prevention had received reports of more than 6,000 cases of AIDS in children infected before or during birth or through breast-feeding, as of Dec. 31, 1995. Not surprisingly, experts predict that as more women of childbearing age become infected, the number of infected children will also rise. A disturbing prospect under any circumstances, the significance of this projection is most poignant for minorities in New York City, where AIDS is already the leading cause of death in Hispanic children 1 to 4 years of age and the second leading cause of death for African American children of the same ages.
Marian Segal is a member of FDA's public affairs staff. Judith Levine Willis also contributed to this article. This article originally appeared in the October 1993 issue of FDA Consumer Magazine, revised September 1997.