1. Gynecology-Obstetrics Hospital, Poznan University of Medical Sciences, 60-535 Poznan, Poland
2. Department of Maternal and Child Health, Poznan University of Medical Sciences, 60-701 Poznan, Poland
3. Students’ Scientific Association, Poznan University of Medical Sciences, 60-701 Poznan, Poland
4. Greater Poland Specialist Centre, 60-479 Poznan, Poland
5. Department of Immunobiology, Poznan University of Medical Sciences, 60-701 Poznan, Poland
6. Facility of Practical Midwifery Teaching, Poznan University of Medical Sciences, 60-701 Poznan, Poland