Pregnancy and birth rates among HIV-infected women in the United States: the confounding effects of illicit drug use

OBJECTIVE: To determine the effect of HIV infection on pregnancy and birth rates and assess the potentially confounding effect of illicit drug use. DESIGN: A retrospective record review of matched cohorts examining pregnancy outcomes for HIV-positive women and two HIV-negative comparison groups (one matched by drug use). METHODS: Ninety HIV-positive women who gave birth in a US city between 1989 and 1993 were matched to HIV-negative women by race, age, parity and date of index birth (group 1, N = 180) and also by the type of illicit drug used (group 2, N = 90). Data were abstracted on tubal ligations and pregnancies occurring before April 1996. RESULTS: A total of 63% of HIV-positive women used cocaine during the index pregnancy and 26% also used opiates. HIV-positive women had fewer tubal ligations than group 1 (38.9% versus 51.1%, P = 0.058), but there was no difference when matching included drug use (38.9% in group 2). HIV infection was associated with a decrease in the number of pregnancies; this decrease was most marked when matching included drug use (18.0 versus 32.1 pregnancies per 100 woman-years,P < 0.01). There were no significant differences in spontaneous or therapeutic terminations. Poisson regression analysis demonstrated that HIV infection and older age were associated with fewer pregnancies, and cocaine use with an increased pregnancy rate. CONCLUSION: This study confirms that HIV infection is associated with a decrease in the number of pregnancies, but also illustrates the confounding effects of illicit drug use among women in the United States.