Many studies have been undertaken in the last 10 years to determine the prevalence of both human immunodeficiency virus (HIV) infection and drug use in pregnant women. These studies could have a serious impact on the delivery of health care as well as the development of health policy. We provide an overview of the key findings from these studies and a critical review of their strengths and weaknesses. For example, although many prevalence studies were conducted with enough participants to reach statistical significance, flaws in study design limit the generalizability of the findings. In addition, the development of profiles, risk groups, or characteristics was an unsuccessful method of identifying pregnant women at risk for drug use or HIV infection. These findings have implications for the type of screening procedures that are undertaken in the clinical setting and the development of health policy at various levels of government. We also conclude that the issue of stigma and discrimination in relation to drug and HIV testing, as well as race, gender, and socioeconomic status, must be addressed. Finally, we outline how these studies could have a significant effect on the health of pregnant women.