1 Department of Obstetrics and Prenatal Medicine, Asklepios Klinik Barmbek, Ruebenkamp 220, 22307, Hamburg, Germany. [email protected].
2 Faculty of Medicine, Philipps-University of Marburg, Marburg, Germany. [email protected].
3 Faculty of Medicine, Philipps-University of Marburg, Marburg, Germany.
4 Department of Obstetrics and Gynecology, Vivantes Klinikum Berlin, Berlin, Germany.
5 Stastistical Institute, Berlin, Germany.
6 German Reference Centre for Pregnancy-Associated Osteoporosis, Department of Osteoporosis, Endocrinology and Reproductive Medicine, Frankfurt, Germany.