Mother-to-Child HIV Transmission Decreases in the U.S. But Challenges Remain For Perinatal Prevention

As the lead federal agency for preventing HIV, CDC has several key responsibilities: surveillance of the American epidemic; biomedical and behavioral prevention research; support of prevention programs and provision of technical assistance; evaluation of what works; strategic communications; and HIV/AIDS prevention technical assistance to states and communities. Recent reductions in mother-to-child, or perinatal, HIV transmission reflect the effectiveness of this multi-level prevention strategy. Challenges remain -- chief among them the need to ensure pregnant women have prenatal care early in pregnancy and can sustain care throughout pregnancy and beyond.

Increasing Impact on Women

Through December 1994, CDC received reports of 58,428 cumulative cases of AIDS among adult and adolescent women (13 years of age and older) in the U.S. Women account for more and more AIDS cases--they were only 7% of all AIDS cases in 1985, but jumped to 19% in 1995. AIDS is now the third leading cause of death among women 25-44. And AIDS is actually increasing faster in women than it is in men. In 1994 alone, 14,081 women were reported with AIDS. Women of childbearing age account for the vast majority of those cases: 84% were reported in women 15-44 years old. In 1993, an estimated 7,000 HIV-positive women gave birth in the U.S., or about 1 in every 625 births. Not every baby born to an infected mother is also infected. In fact, without preventive treatment, the mother-to-child transmission rate was 15-30%, or about 1,000-2,000 infants in 1993.

In 1994, clinical trials in the U.S., Canada, and France conducted by America's National Institutes of Health and France's National Institute of Health and Medical Research (INSERM) showed that some HIV-infected women could reduce the risk of transmitting the virus to their babies by as much as two-thirds by taking zidovudine (ZDV or AZT) during pregnancy, labor and delivery, and by giving their babies AZT for the first 6 weeks after birth. In 1994, CDC issued guidelines for using AZT during pregnancy and, in 1995, published guidelines for routinely counseling all pregnant women about HIV and offering them an HIV test.

What's Working To Prevent Mother-to-Child Transmission

The guidelines for routine counseling and voluntary testing, coupled with AZT treatment if the mother is HIV infected, are showing positive effects on the American perinatal transmission rate.

Among women in CDC's Perinatal AIDS Collaborative Transmission Study (PACTS), AZT use increased following the publication of CDC guidelines. In 1994, after the guidelines were published, the women and children enrolled in PACTS had an 11% rate of perinatal transmission

-- down from 21% before the guidelines, and lower than ever before. And the effect of other factors on mother-to-child transmission -- such as the mother's stage of AIDS and CD+4 count, and the elapsed time from rupture of membranes (water breaking) to delivery -- is becoming more clear, making early and sustained prenatal care vital to preventing perinatal transmission.

Prenatal Care Is Vital To Preventing Perinatal Transmission

Related studies by CDC researchers address the role of other factors, particularly prenatal care, in reducing mother-to-child transmission and pediatric AIDS.

• Behavioral research demonstrates that the majority of women infected with HIV are interested in AZT treatment during pregnancy and for their children after birth. But women's interest and commitment to adhering to the AZT treatment regimen seems particularly sensitive to obstetricians' attitudes, underscoring the importance of educating health care providers about the benefits of AZT during pregnancy.

• Another study shows that AZT use has increased since the publication of CDC's treatment guidelines, but, early on, was variable by hospital. Researchers examined AZT rates in hospitals in the New York City area, Atlanta and Baltimore and found that usage ranged from 33% of enrolled mothers to 90%, depending on the hospital and the populations it served. The lowest rates of AZT use were among women who used cocaine during pregnancy and women with fewer AIDS-related illnesses. Researchers continue to examine usage rates to determine their increase over time, and to determine health care workers' and pregnant women's attitudes to treatment regimens.

• Researchers are studying the association of HIV transmission and no or late prenatal care with demographic, social, and other characteristics of infected women in Texas. The data show that some women receive very late or no prenatal care and that lack of timely care is associated with drug use, having less than 12 years of education and being unmarried. To further reduce perinatal HIV transmission and other adverse pregnancy outcomes, comprehensive interventions to increase early prenatal care are needed.

• Related behavioral research shows breastfeeding is much more common -- though still rare, at less than 1% -- among women whose HIV infection is not known before delivery. In contrast, infected women who received comprehensive prenatal care, including counseling and voluntary HIV testing, were less likely to breastfeed their babies.

Routine Counseling, Voluntary Testing, and AZT Are Cost-Effective

Economic analysis shows that prenatal care, including HIV counseling and testing and AZT for infected mothers and their children, is cost effective. Without intervention, a 25% mother-to-infant transmission rate would result in 1,750 HIV-infected infants annually in the U.S., and lifetime medical costs of $282 million. Researchers estimated the cost of intervention at $67.6 million, preventing 656 infant HIV infections and a savings of $105.6 million in medical care costs, and a net cost-savings of $38.1 million. These results strongly support routine counseling, voluntary testing, and AZT use.

It is possible that these savings could be increased, if research shows a shorter course of ZDV during pregnancy is just as effective. Several clinical trials of short-course ZDV during pregnancy are underway in sub-Saharan Africa. In developing countries, the extensive ZDV course used in the U.S. is not feasible. If it can be demonstrated that a short course works, it will be a promising advance for addressing the terrible toll perinatal transmission takes internationally. A model presented by a CDC researcher indicates that a national perinatal HIV prevention program in most sub-Saharan African countries would reduce transmission and provide significant societal savings, after the substantial initial investment in public health infrastructure and drugs.

PERINATAL PRESENTATIONS IN VANCOUVER

Cost Effectiveness of Short-Course Zidovudine to Prevent Perinatal Human Immunodeficiency Virus Type-1 Infection in a Sub-Saharan African Developing Country Setting, Gordon Mansergh.

Declining Mother-to-child HIV Transmission Following Perinatal Zidovudine Recommendations, United States, R. J. Simonds.

Perinatal HIV Transmission Risk and the Effect of Pregnancy or Infant Zidovudine Use in a Multicenter Study, 1994-1995, Richard W. Steketee.

Poster

Breastfeeding Among HIV-Infected Women, Los Angeles and Massachusetts, 1988-1993, Jeanne Bertolli.

Early Diagnosis of Perinatal HIV Infection Comparing DNA-Polymerase Chain Reaction and Plasma Viral RNA Amplification, Teresa M. Brown.

Preventing Perinatal HIV Infection: Costs And Effects Of A Recommended Intervention In The U.S., Paul. G. Farnham.

Detection of Phylogenetically Linked HIV Strains Among a Population of Epidemiologically Unrelated Women, Marcia L. Kalish.

Perinatal Zidovudine Use after Perinatal ZDV Recommendations in the United States, Sherry L. Orloff.

Lack Of Timely Prenatal Care Among Women Infected With HIV: Implications For Prevention Of Perinatal HIV Transmission In The United States, Anna Shakarishvili.