Most large surveys have come to similar conclusions regarding the effectiveness of nitrous oxide in labour when it is used properly. Rather less than 50 per cent of women claim satisfactory relief: 20 per cent obtain some relief for some of the time, and approximately 30 per cent find it completely ineffective. Nitrous oxide very rarely relieves contraction pain altogether. It is not as effective during labour, therefore, as it is with other painful conditions, such as bone fractures and burns. This is because uterine contractions are obviously more painful.