1 Obstetrics and Gynaecology Unit, Department of Health Sciences, University of Florence, Florence, Italy. Electronic address: viola.seravalli@unifi.it.
2 Obstetrics and Gynaecology Unit, Department of Health Sciences, University of Florence, Florence, Italy.
3 Department of Chemistry "U.Schiff", University of Florence, Florence, Italy.
4 Department of Statistics, Computer Science, Applications, University of Florence, Florence, Italy.
5 Obstetrics and Gynaecology Unit, Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy.