Human immunodeficiency virus (HIV) seroprevalence among pregnant women varies between and within countries and is generally higher in urban than in rural areas. In the European Collaborative Study, heterosexual transmission is increasing and most women are asymptomatic, although the overall mean CD4 count is declining over time. There seems to be little evidence of an increased risk of pregnancy or delivery complications in HIV-infected pregnancies. Most studies have found no increase in adverse pregnancy outcomes, although further research is needed. Prospective studies suggest that pregnancy does not promote accelerated disease progression in asymptomatic women. Despite earlier concerns, three recent studies suggest that pregnancy is not associated with deterioration of immunocompetence. The increasing number of infected pregnant women requires adequate planning for the future care of their children.