1. Faculty of Medicine , University of Porto , Porto , Portugal , Tel.: +351938619352
2. Hospital S. João, Alameda Professor Hernâni Monteiro , 4200-319 Porto , Portugal
3. Department of Pathology, Centro Hospitalar de S. João , Porto , Portugal
4. Department of Obstetrics and Gynaecology, Centro Hospitalar de S. João, Faculty of Medicine, EPIUnit , University of Porto , Porto , Portugal
5. Department of Obstetrics and Gynaecology, Centro Hospitalar de S. João, Faculty of Medicine , University of Porto , Porto , Portugal