[Diagnosing the onset of labour: more than a definition issue]

Because the onset of labour represents a genuine diagnostic problem, labour at term is usually ascertained based on undefined subjective criteria. This can have far-reaching consequences. When the onset of labour is not duly diagnosed, dysfunctional labour may remain unrecognized and timely treatment could be wrongly withheld. Conversely, when a woman is declared to be in labour too early, erroneous interventions may follow. It is assumed that correct diagnosis of the onset of labour contributes to the effective correction of slow progression and to a reduction in the rising caesarean section rate. To diagnose the onset of labour, knowledge of physiology as well as pathophysiology in labour is required. A plea for verbal clarity amongst caregivers as well as consistent, evidence-based diagnosis of the onset of labour is made in this article.