This book provides the first systematic and in-depth epidemiological treatment of prenatal development, from fertilization to birth. It lays the groundwork for causal thinking about prenatal development by discussing criteria for evaluating observed associations between teratogens and developmental outcomes. The authors map development epidemiologically, dealing with the probabilities of conception and early loss, the relation between miscarriage and chromosome abnormalities, and the questions of recurrence and environmental influences on pregnancy loss. The discussion of fetal growth distinguishes between preterm delivery, retarded growth, and immaturity. Indices for measuring growth are analyzed. The predominant maternal and environmental influences on prenatal growth and birth weight are reconciled with the genetic contribution to postnatal growth. Finally, the book examines the major issues of maternal age and parity, and addresses the public health challenge of monitoring and surveillance. As a unique synthesis of epidemiological knowledge, this volume perfectly complements the more well-known work being done in prenatal development in the fields of biology, physiology, and genetics.