ABSTRACT: Among the many physiologic changes that occur during pregnancy, the maternal immune system is altered to dampen the maternal inflammatory response and allow for fetal antigen tolerance 1 2. Although such immunologic changes diminish the chance of fetal rejection, they potentially increase maternal and fetal vulnerability to certain infectious diseases. Common infections that cause mild-to-moderate disease in healthy adults and children can cause serious maternal and fetal complications if acquired during pregnancy. A unique concern with maternal infection is the potential for mother-to-child transmission or congenital infection. Cytomegalovirus (CMV), parvovirus B19, varicella zoster virus (VZV), and toxoplasmosis are common infections associated with moderate-to-severe fetal and infant complications when acquired congenitally. The purpose of this document is to update the current understanding of these infections, including their clinical presentations; their modes and risks of perinatal transmission; and their maternal, fetal, and infant effects, and to offer guidelines for preventing and managing these infections during pregnancy.