This article discusses a variety of issues related to pregnancies complicated by substance use. Drug use is most prevalent in the reproductive age population. Even though a reduction in substance use may occur during pregnancy, some women may not alter their drug use patterns until pregnancy is diagnosed. For these reasons, a large number of fetuses are exposed to illicit substances in utero. Care of substance-using pregnant women is complex, difficult, and often demanding. Providers must be aware of their unique psychologic and social needs, and the related legal and ethical ramifications surrounding pregnancy.