Infectious diseases have a broad spectrum of effects on reproduction. Infections inflict their most serious damage on fertility, embryogenesis, and fetal development. Preterm delivery, particularly very preterm delivery, is emerging as an end point to which infections may make a major contribution. Infections have more subtle and disputed effects on the risk of miscarriage and impaired fetal growth. Understanding the impact of infectious diseases on reproductive outcomes allows the clinician to better evaluate and counsel the patient affected by these diseases. A thorough understanding of the acquisition, natural course, and pathological sequelae of infectious diseases on the various stages of reproduction will complement the interpretation of reproductive epidemiologic studies that can further guide clinical management.