1. Department of Obstetrics and Gynaecology, Rīga Stradiņš University, LV-1007 Riga, Latvia
2. Riga Maternity Hospital, LV-1013 Riga, Latvia
3. Department of Obstetrics and Gynaecology, Lithuanian University of Health Sciences, 50167 Kaunas, Lithuania
4. Riga East Clinical University Hospital, LV-1038 Riga, Latvia