[What is the duration of normal labour?]

A third of all pregnant women in Norway have slow progress of labour, and almost as many have their labours augmented. Midwives and obstetricians do not agree about the duration of normal labour. The aim of the present study was to review textbooks, guidelines and studies to assess how the 1 st and 2 nd stages of labour were defined and how duration of the stages was described.

Syllabus lists, websites and on-line bookstores were searched for textbooks and guidelines and the databases MEDLINE and MIDIRS were searched for scientific studies published in 1995 and later. Additional studies were found in the reference lists of the studies identified.

Eight textbooks, 7 guidelines and 9 studies were found to be relevant. Definitions of birth onset, its phases and duration varied; i.e. onset of the latent phase of the 1 st stage of labour and onset of the 2 nd stage. Onset of the active phase was defined almost identically at a cervical dilatation of 3-4 cm. Some textbooks and guidelines divided the 2 nd stage in two phases: the latent and active phase. The end of the 2 nd stage was always defined as the birth of the baby.

Definition of a normal duration of labour lacks scientific support. As many women are assessed to have slow progress of labour, the duration of labour should be systematically recorded. Prospective studies are needed on labour duration, the consequences of prolonged labour and the appropriate timing for intervention.