Increased perinatal use of invasive monitoring techniques and a higher rate of cesarean section have led to an increase in the rate of maternal infection and to new types of infections in newborns. Control measures for maternal infections include antibiotic prophylaxis, direct administration of antibiotics to the amniotic fluid, extraperitoneal cesarean section, and cesarean hysterectomy. New types of infections in newborns include abscess resulting from use of electrodes to monitor fetal heart rate and the development of group B beta hemolytic streptococci infection, particularly in association with prolonged rupture of maternal membranes. Prospective studies are needed of preventive measures and proper management of maternal and perinatal infections. Obstetric and gynecologic problems that need further investigation include pelvic infection after vaginal hysterectomy, salpingooophoritis, and antibiotic dosages for pregnant women.