1. The Department of Obstetrics and Gynecology; University of Helsinki and Helsinki University Hospital; Helsinki Finland
2. National Institute for Health and Welfare; Oulu Finland
3. Biobank Borealis of Northern Finland; Oulu University Hospital; Oulu Finland
4. Virology and Immunology; University of Helsinki and Helsinki University Hospital; Helsinki Finland
5. Faculty of Medicine; University of Oulu; Oulu Finland