Duration of human immunodeficiency virus infection and likelihood of giving birth in a medicaid population in Maryland

The objective of this study was to examine the effect of duration of human immunodeficiency virus (HIV) infection on a woman's likelihood of giving bi rth. Using longitudinal data from the Maryland state Human Immunodeficiency Virus Information System and a retrospective cohort design, the authors co mpared 1,642 women with acquired immunodeficiency syndrome (AIDS) to 8,443 uninfected women enrolled in the Medicaid program between 1985 and 1995. Th e decade before AIDS diagnosis was divided into four 2.5-year periods. Prox imity to AIDS diagnosis served as a proxy for duration of infection. An ext ension of the Cox model was used to estimate the relative risk for giving b irth, with adjustment for covariates and repeated outcomes. The average num ber of births per 100 person-years was 6.0 for HIV-infected women and 11.1 for uninfected women (adjusted relative risk = 0.63; 95% confidence interva l (Cl): 0.57, 0.68). Accounting for duration of infection, the adjusted rel ative risks for birth among HIV-infected women, as compared with uninfected women, were 0.85 (95% CI: 0.71, 1.03), 0.74 (95% CI: 0.63, 0.86), 0.55 (95 % CI: 0.47, 0.64), and 0.45 (95% CI: 0.38, 0.55) for successive 2.5-year pe riods before AIDS diagnosis. Demographic characteristics, contraception, ab ortion, fetal loss, or drug use could not fully explain the reductions. The se results suggest that HIV-infected women experience a progressive reducti on in births years before the onset of AIDS. This may compromise estimation of HIV prevalence and interpretation of time trends from serosurveillance of pregnant women.