1. Department of Obstetrics and Gynecology, Kanta-Häme Central Hospital, Hämeenlinna, Finland
2. Department of Obstetrics and Gynecology, Tampere University Hospital, Tampere, Finland
3. Department of Microbiology, Fimlab Laboratories Ltd., Tampere, Finland
4. Department of Obstetrics and Gynecology, Central Finland Health Care District, Jyväskylä, Finland
5. School of Medicine, University of Tampere, Finland