1. Division of Obstetrics and Gynecology; Department of Clinical Sciences; Karolinska Institute; Danderyd Hospital; Stockholm Sweden
2. Obstetrics and Gynecology; Department of Clinical and Experimental Medicine; Faculty of Medicine; Linköping University; Linköping Sweden
3. Department of Pediatrics; Women and Infants Hospital; Warren Alpert Medical School of Brown University; Providence RI USA