High incidence of maternal parvovirus B19 infection in a large unselected population-based pregnancy cohort in Norway.

•High incidence of viremic B19V infections and seroconversion rates were recorded in this cohort of randomly selected pregnant women.•A combination of serology and PCR is essential for diagnosing parvovirus B19 infection in pregnant women.•Lack of seroconversion despite longstanding viremia emphasizes the importance of including PCR when testing for infection during pregnancy.•Vertical transmission of B19V was seen in 20% of mothers with confirmed infection and in 28% of B19V viremic mothers.