During an outbreak of fifth disease in the Hartford, Connecticut area in the winter of 1986, nine pregnant women were exposed to the parvovirus. Five of these nine had serologic evidence of previous exposure and immunity; all five had uneventful pregnancies. Three of the four women who exhibited serologic evidence of recent exposure to the parvovirus had hydropic fetuses who died, one of whom was anencephalic. Histologic and DNA hybridization studies suggest parvovirus infection as a cause for nonimmune hydrops and fetal death. A review of the literature suggests that of 37 women who were exposed and infected by human B19 parvovirus during pregnancy, 14 (38%) had adverse outcomes, including spontaneous abortions, intrauterine fetal death, and congenital anomalies. Women at high risk for exposure (school teachers) should have screening for immunoglobulin G parvovirus-specific antibodies; if these are absent, they should avoid close contact with schoolchildren. Pregnant women with evidence of recent infection should have a level II ultrasound. Because no vaccine is currently available, routine screening cannot be recommended.