The prevalence of HIV-1 among women of reproductive age is currently e
stimated at the time they give birth. We assessed HIV-1 prevalence at
the end of pregnancy, whether they delivered or had an induced or spon
taneous abortion. Women admitted at the end of pregnancy to hospitals
in the Lazio Region, Italy, were tested for antibodies to HIV-1. Conse
nt for testing was granted by 97.1% of 218,357 subjects; women who did
not consent were tested anonymously. The prevalences of infection wer
e 0.34% in 1989, 0.38% in 1990, 0.28% in 1991, 0.23% in 1992, 0.28% in
1993, and 0.24% in 1994. Significantly higher prevalences of infectio
n were associated with induced abortion (0.49%) than with delivery (0.
18%; OR: 2.72; 95% CI: 2.29-3.22) and among women who refused (0.85%)
than among those who consented to testing (0.27%; OR: 3.14; 95% CI: 2.
35-4.19). A significant temporal reduction in prevalence was observed
only among women who delivered (0.15% in 1993 and 1994; 0.26% in 1989
and 1990). The prevalence of HIV-1 infection is thus higher among wome
n undergoing induced abortions than among those who deliver and higher
among women who refuse testing than among those who consent. Studies
confined to neonatal testing or to voluntary testing of pregnant women
would thus underestimate the prevalence of HIV-1 among women of repro
ductive age.