1. Department of Gynecology and Obstetrics, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
2. Institute for Medical Informatics, Biometry and Epidemiology, University Hospital, University of Duisburg-Essen, 45147 Essen, Germany
3. Department of Neurosurgery and Spine Surgery, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
4. Department of Nephrology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
5. Department of Pediatrics I, Division of Neonatology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany
6. Department of Gynecology and Obstetrics, St. Hedwig’s Clinic of the Order of St. John, University Regensburg, 93053 Regensburg, Germany