Maternal and fetal infections during pregnancy have the potential to cause severe complications for both the mother and the fetus. Addressing these infections promptly and effectively is crucial to prevent adverse outcomes such as preterm birth, intrauterine growth restriction, congenital anomalies, and neonatal morbidity and mortality. This chapter will provide a comprehensive overview of the pathophysiology, risk factors, diagnosis, and management of maternal infections while highlighting maternal and fetal outcomes associated with each infection. Ultrasonographic findings and their associated maternal-fetal infections have been included to help guide practitioners to take explorative measures based on concerning findings and to increase provider awareness of signs of maternal-fetal infection, leading to earlier intervention.