This study is designed as a single-blind randomized clinical trial with parallel design, and third party evaluation at the Hospital Universitario Príncipe de Asturias in Alcalá de Henares (Madrid, Spain). The study will be carry out with primiparous women who were in labour at this hospital. Information sheets about the study will be distributed by the different health care centers coordinated by the hospital. The midwives will give the information sheets to pregnant women during the pregnancy's attendances. The aim is to let pregnant women know about the study before their labour date in order to encourage them to participate in it.