Progression of the first stage of spontaneous labour.

This chapter reviews and compiles the most recent published evidence assessing the overall labour duration and patterns of progression for both nulliparous and parous women, as well as the accuracy of the alert and action lines in the World Health Organization (WHO) partograph for the identification of women at risk of birth complications. Systematic reviews of observational studies reporting on the duration of the first and the second stages of labour, and on cervical dilatation patterns for women with low risk of complications with 'normal' perinatal outcomes were identified and updated. The accuracy of the alert (1 cm/h) and action lines of the cervicograph in the partogram to predict adverse birth outcomes among women in first stage of labour was also reviewed, questioning the appropriateness of considering cervical dilatation over time as an isolated indicator to define labour progression or arrest.