The major goals of this study were to measure the current prevalence and estimate the annual incidence of HIV-1 infection in young pregnant women from urban Malawi, to identify factors that were associated with HIV-1 infection, and to examine adverse pregnancy outcomes. Four hundred and sixty-one consecutive pregnant women were studied when they presented for prenatal care. The overall seroprevalence for HIV-1 infection in these urban populations was 17.6% (81 out of 461) during early 1989. Based on previous seroprevalence in similar unselected pregnant women, the estimated annual incidence of HIV-1 seroconversion in urban pregnant women ranged from 3 to 4% per annum between 1985 and 1987 and from 7 to 13% between 1987 and 1989. HIV-1 infection was significantly associated with reactive syphilis serology. Reported history of sexually transmitted disease was also correlated with HIV-1 infection but was not statistically significant. Other variables, such as history of transfusion, history of tuberculosis, parity or occupation were not associated with HIV-1 infection. History of spontaneous abortion was significantly associated with reactive syphilis serology, HIV-1 infection and history of sexually transmitted disease. In logistic regression analysis, HIV-1 infection remained the only significant variable that was correlated with spontaneous abortion. This study suggests that HIV-1 infection may play a role in fetal wastage.