1. Department of Obstetrics and Gynecology, Kalmar County Hospital, 391 85 Kalmar, Sweden
2. Department of Clinical Physiology, Kalmar County Hospital, 391 85 Kalmar, Sweden
3. Department of Medicine and Health Sciences, Linköping University Hospital, 581 85 Linköping, Sweden
4. Department of Obstetrics and Gynecology, and Department of Clinical and Experimental Medicine, Linköping University, 581 83 Linköping, Sweden