The purpose of each issue of Seminars in Perinatology is to provide authoritative and comprehensive reviews of a single topic of interest to professionals who care for the mother, the fetus, and the newborn. The journal's readership includes perinatologists, obstetricians, pediatricians, epidemiologists, students in these fields, and others. Each issue offers a comprehensive review of an individual topic, with emphasis on new developments that will have a direct impact on their practice.