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May 15, 2000

Fertility Rate of HIV-infected Women Is 37 Percent Less Than That of Healthy Women

A study by researchers at the Johns Hopkins School of Public Health examining the effect of the human immunodeficiency virus (HIV) on fertility has indicated that women infected with HIV give birth to progressively fewer babies as they near the onset of frank AIDS. HIV incubates for an average of ten years before causing AIDS, and the scientists were able to detect significant declines in fertility as early as two to five years after HIV infection. The study appeared in the May 2000 issue of the American Journal of Epidemiology.

The prevalence of HIV infection in the general population is currently estimated under the assumption that women with HIV have fertility patterns similar to those without the infection. Senior author Ronald H. Gray, MD, professor, Population and Family Health Sciences, Johns Hopkins School of Public Health, said, "If, as our findings strongly suggest, women with HIV are less likely to become pregnant or to give birth to a live infant, then the HIV infection rates monitored through antenatal and delivery services could be misleading, and rates among women of childbearing age could be seriously underestimated."

The study population included women of reproductive age (15-44 years) who were residing in the state of Maryland and were covered by Medicaid between 1985 and 1995. This population -- largely minority, poor, and urban -- was similar to the population of women at highest risk for HIV and AIDS in the United States. The 1,642 HIV-infected women in the study were identified at the time of AIDS diagnosis; the study's 8,443 HIV-negative women were selected from Medicaid enrollees covered at any point during 1990 through 1995.

The researchers controlled for potential confounding variables, including: age; use of induced abortion or contraceptives; tubal ligation or other sterilization procedures such as hysterectomy; pelvic inflammatory disease; alcohol or illicit drugs; and diabetes mellitus. The participants; socioeconomic status was controlled for, since both cohorts were restricted to the Medicaid population, which is by definition near or below federal and state poverty levels.

To assess how current methods of HIV surveillance might be affected by a reduction in fertility among HIV-infected women, the authors measured the prevalence of HIV infection in those women who gave birth and in those who did not in each year from 1985 through 1995. "HIV prevalence declined progressively among women who gave birth, and increased among women who did not give birth," said first author Lisa M. Lee, BS, MA, a graduate student in Population and Family Health Sciences at the Johns Hopkins School of Public Health. "Thus, surveillance for HIV via maternal or obstetric clinics could lead to biased estimates of the prevalence of HIV in the population of reproductive age."

The researchers then tallied births (including induced abortions and miscarriages) per 100 person-years in HIV-infected women for up to ten years before the AIDS diagnosis, and compared those numbers with births per 100 person-years among uninfected women. The average number of births per 100 person-years was 6.0 in HIV-infected women, compared with 11.1 for uninfected women, a difference of 37 percent.

The reduction in fertility among HIV-infected women became more pronounced as the time to AIDS diagnosis grew shorter. Assuming that most of the women with AIDS had been infected roughly ten years before diagnoses, the scientists subdivided the decade preceding AIDS diagnosis into four 2.5-year intervals: 10 to 7.5, 7.5 to 5, 5 to 2.5, and 2.5 to 0 years. The most distant period before AIDS diagnosis (10.0 to 7.5 years) didn't significantly influence the likelihood of an HIV-infected woman giving birth; however, HIV-infected women gave birth only 74 percent as often as uninfected women in the 7.5 to 5.0-year period before AIDS diagnosis, 55 percent as often in the 5.0 to 2.5 quarter, and 45 percent as often in the 2.5 to 0 quarter.

Demographic characteristics, contraceptive use, induced abortion, recognized fetal loss, other medical diagnoses, or illicit drug use could not explain these reductions in fertility. Induced abortions were more common in HIV-infected than uninfected women; however, the reduction in births among HIV-infected women persisted after adjustment for abortion.

Support for this study was provided in part by grants from the Association of Schools of Public Health, the Public Health System Fellowship, and the National Institute of Child Health and Human Development.

Public Affairs Media Contacts for the Johns Hopkins Bloomberg School of Public Health: Tim Parsons or Kenna Brigham @ 410-955-6878 or paffairs@jhsph.edu.