The purpose of this study was to describe the content of prenatal care in the United States over time. Secondary data sources were reviewed and selected data were analyzed, mainly in the last two decades. Data reviewed included special surveys from the National Center for Health Statistics, advice given by professional organizations, obstetric textbooks, commercial advertisements in obstetric journals, and occasional surveys. The data suggest that American prenatal care has emphasized screening for biomedical problems, while health education and support functions have been less central. It appears that some prenatal practices from earlier years, such as strict weight-gain restriction, wide use of diuretics and some other drugs, use of x-ray, have been harmful.