Pregnancy anxiety is a particular emotional state tied to pregnancy-specific concerns, such as worries about the health of the baby and childbirth. A growing body of research demonstrates that pregnancy anxiety is an important risk factor for preterm birth and other adverse birth and child development outcomes. This article defines and describes the concept of pregnancy anxiety, provides a summary of evidence linking pregnancy anxiety to outcomes, and identifies characteristics of women and their pregnancies that contribute to high levels of pregnancy anxiety. The authors also discuss possible clinical implications and interventions to reduce pregnancy anxiety.