The placenta generally provides a robust barrier to the fetal compartment and relatively few microbes are able to surmount this and other defenses at the maternal-fetal interface to cause congenital infections. Nonetheless, congenital pathogens including human cytomegalovirus, Zika virus, Toxoplasma gondii, and group B streptococcus can cause fetal loss, growth restriction, birth defects, and developmental delays. In addition to pathogenic effects on the fetus and neonate, infections during pregnancy can have distinct impacts on maternal health, owing to the physiologic and immunologic effects of pregnancy. There is a need to better understand the pathogenic mechanisms of congenital infections and immune defenses at the maternal-fetal interface,as well as to develop improved vaccine, treatment, and diagnostic strategies to combat congenital infections. But in many cases these infections can be difficult to study due to limitations in experimental systems and challenges in designing studies with human patients. This symposium will bring together researchers investigating infections in pregnancy from a range of perspectives including basic biology, pathogenesis models, clinical studies, and patient care. Goals of this Keystone Symposium are: i) Highlight new advances in understanding the pathogenic mechanisms of congenital infections. ii) Share new developments in experimental systems for studying congenital infections, as well as new developments in vaccines, therapeutics, and diagnostics. iii) Consider the effects of infections during pregnancy on maternal health, as well as on fetal, infant, and child health. iv) Provide an opportunity for researchers from diverse backgrounds to exchange ideas and develop new collaborations to promote future research on infections during pregnancy.