To identify exposures associated with parvovirus B19 infection during pregnancy, two groups of pregnant women were studied during an outbreak of erythema infectiosum (EI). Of 796 pregnant women from Connecticut who were tested serologically because of perceived exposure to B19, 53% (419/796) had serologic evidence of previous B19 infection, and 6% (23/376) of the rest had evidence of recent infection. Of 121 pregnant women who had not requested testing but who lived in a community where a large outbreak of EI had occurred among schoolchildren, 36% (43/121) had serologic evidence of previous infection, and only 3% (2/78) of the rest had had a recent infection. In the exposed group, 479 women returned a supplemental exposure questionnaire. The highest infection rates among susceptible women were for schoolteachers (16%, 10/64), followed by day care workers (9%, 2/22) and homemakers (9%, 4/46). Women working outside the home but not in school or day care settings had the lowest risk (4%, 3/80). This study suggests that there is risk for B19 infection in selected occupational settings and in households.