Intrapartum fetal infection by herpes simplex virus (HSV) is invariably symptomatic and often times fetal. Infection is usually associated with an active maternal genital infection with virus shedding at the time of delivery. Current recommendations call for weekly culturing of cervico/vaginal specimens to detect infectious virus. If a positive culture appears, caesarean rather than vaginal delivery is implemented. Monitoring by virus isolation has an obvious shortcoming in that detection of HSV in permissive cells may take several days. Thus, the chance of identifying an active genital HSV infection at the critical time of delivery is minimized. We propose to develop an immunologic test employing antibodies to HSV for the early detection of active HSV infections in pregnant women at or near the time of delivery.