BACKGROUND Parvovirus infection during pregnancy has been reported to be associated with spontaneous abortion and fetal loss. OBJECTIVE To show the incidence of antibodies against Parvovirus B19 early in pregnancy and sero-reactivities during and after pregnancy. METHODS In a prospective study during a non-epidemic period, 457 women admitted to an antenatal care center were included. Serum samples were collected at 7-13, 21, and 33 weeks of gestation, and 7-9 weeks after delivery. METHODS Samples were evaluated for parvovirus specific IgG and IgM against two different parvovirus antigens. CONCLUSIONS Parvovirus specific antibodies were present in 81% of the women in the first sample. Six women (six of 88 susceptible, 6.8%) seroconverted and 28 women (28/369, 7.6%) boosted their antibody response during or after pregnancy. All gave birth to healthy infants. One woman free of symptoms experienced an intrauterine fetal death at 37 weeks of gestation. She had no rise in B19 antibodies during pregnancy, but parvovirus DNA was found in maternal serum samples and in the placenta.