Sexually transmitted infections remain a major public health concern in the United States. An estimated 19 million infections occur each year. The economic burden imposed by sexually transmitted infections is impressive: direct medical costs have been estimated as high as 15.5 billion US dollars annually. Sexually transmitted infections are relatively common during pregnancy, especially in indigent, urban populations. Education, screening, treatment, and prevention are important components of prenatal care for women at increased risk for these infections. Treatment of these sexually transmitted infections is clearly associated with improved pregnancy outcome and reductions in perinatal mortality.