1. Department of Periodontology; Center for Dentistry and Oral Hygiene; University of Groningen; University Medical Center Groningen; Groningen The Netherlands
2. School of Health Care Studies; Hanze University of Applied Sciences Groningen; Groningen The Netherlands
3. Department of Obstetrics and Gynecology; University of Groningen; University Medical Center Groningen; Groningen The Netherlands
4. Division of Medical Biology; Department of Pathology and Medical Biology; University of Groningen; University Medical Center Groningen; Groningen The Netherlands