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Increased risk of human parvovirus B19 infection in day-care employees: a cohort study among pregnant workers during an epidemic in Finland
  1. Anita Riipinen1,2,3,
  2. Markku Sallmén1,
  3. Lea Hedman2,4,
  4. Anneli Ojajärvi5,
  5. Marja-Liisa Lindbohm1,
  6. Mira Meriluoto2,
  7. Heljä-Marja Surcel6,
  8. Helena Taskinen1,7,
  9. Mika Nuutila8,
  10. Riitta Karikoski9,
  11. Klaus Hedman2,4,
  12. Maria Söderlund-Venermo2
  1. 1Centre of Expertise for Health and Work Ability, Finnish Institute of Occupational Health, Helsinki, Finland
  2. 2Department of Virology, Haartman Institute, University of Helsinki, Helsinki, Finland
  3. 3The Social Insurance Institution of Finland, Insurance Region for Southern Finland, Helsinki, Finland
  4. 4Laboratory Services, HUSLAB, Department of Virology and Immunology, Helsinki University Central Hospital, Hospital District of Helsinki and Uusimaa, Helsinki, Finland
  5. 5Finnish Institute of Occupational Health, Centre of Creating Solutions, Helsinki, Finland
  6. 6National Institute for Health and Welfare, Oulu, Finland
  7. 7University of Helsinki, Hjelt Institute, Helsinki, Finland
  8. 8Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Helsinki, Finland
  9. 9Department of Pathology, Helsinki University Central Hospital, HUSLAB, Helsinki, Finland
  1. Correspondence to Dr Anita Riipinen, The Social Insurance Institution of Finland, Koskelantie 5, Helsinki FI-00610, Finland; anita.riipinen{at}


Background Human parvovirus B19 (B19V) infection during early pregnancy increases the risk of miscarriage. Studies have inconsistently shown an elevated risk of infection among women with occupational contacts with children. Methodological differences, particularly in defining occupational exposure and in the type of reference group, may explain the conflicting findings.

Methods This cohort study compared B19V infections in pregnant day-care employees and healthcare professionals during a B19V epidemic in Finland. Women were identified from the files of nationwide trade unions and the National Supervisory Authority for Welfare and Health. Early-pregnancy maternal B19V IgG was analysed in 3710 women, and infections were defined as seroconversions after analysing in parallel the available umbilical cord blood samples of the 847 seronegative mothers. Independently of the serological status, the actual employment during pregnancy was assessed using registered information on employment history.

Results B19V infections were more common among day-care employees (22/331, 6.6%), than among those working in healthcare (12/326, 3.7%). The adjusted HRs of B19V infection, using proportional hazard regression, was 2.63 (95% CI 1.27 to 5.46) among all women and 5.59 (95% CI 1.40 to 22.4) among nulliparous women.

Conclusions Day-care employees are at an increased risk of B19V infection, which warrants preventive measures.

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