1. Department of Obstetrical-Gynaecological, Urological Science and Reproductive Medicine, Federico II University, Naples, Italy;
2. Department of Electrical, Computer and Biomedical Engineering, University of Pavia, Pavia, Italy;
3. Department of Electronic, Information and Bioengineering, Politecnico of Milano, Milan, Italy;
4. Department of Obstetrics and Gynaecology, Foetal Medicine Centre, University of Rome “Tor Vergata”, Rome, Italy