Vacuum Delivery in All-fours Position vs Traditional Position

The aim of the study is to investigate the safety, clinical efficacy and the maternal/neonatal outcomes of vacuum application in all-fours position compared with supine traditional position, in women undergoing vacuum-assisted delivery during the second stage of labor. The main question it aims to answer are: * Does the rate of failure of vacuum delivery, measured as number of cup detachments and the need of emergency caesarean section is lower if vacuum delivery is performed on a woman in all-fours position? * Do maternal and fetal outcomes are better in case vacuum delivery in all-fours position? Participants will be randomly enrolled at the admission in two different groups, Control and Experimental Group, and in case of need for vacuum-assisted vaginal delivery; women belonging to Control Group will undergo vacuum-assisted delivery in traditional supine position, while women in Experimental Group will experience vacuum application in all-fours position. Researchers will compare the Group A, composed by women who undergo vacuum-delivery in traditional supine position, with Group B, in which women are in "all-fours" position, to see if hands-and-knees position provides better outcomes.