title: [The clinical onset of spontaneous labor in obstetrical research].
abstract: The onset of labour is a cornerstone in the process of childbirth, albeit difficult to define. When a woman's subjective assessment that labour has started is not accompanied by cervical changes, discrepancies can arise between her and her caregivers' perceptions of what labour and childbirth is all about. In this review we examine how definitions and operational terms for the onset of labour evolved and varied with the prevailing paradigms in the clinical research agenda. In the 1950's, the relatively simple concept of labour, divided in a first stage of dilatation and a second stage of expulsion, changed to encompass a latent and active phase of dilatation, based on the work of Friedman and Sachtleben. Later on, the resulting wide variation in the total duration of labour shrank drastically with the emergence of "active management of labour", which required a different operational definition. Subsequently, the transition from observational to controlled clinical research required firmer starting points. Thus, more readily defined starting points, such as admission to hospital or even time of randomisation, replaced the nebulously vague and erratic "onset of labour" in the clinical research agenda. As the paradigms shifted from labour itself to the outcome of labour, the onset of labour and its vagaries became an embarrassment that needed to be overcome. Yet, within the goal of effective care during labour and childbirth, the onset of labour remains as much of a cornerstone as it has been for a long time. Thence outcome-centred thinking may need to take a step back and also embrace process evaluation, if clinical research in maternity care is to achieve its ultimate aim: optimal care for both mother and baby.
authors.affiliation: Abteilung I der Frauenklinik, Medizinischen Hochschule Hannover im Oststadtkrankenhaus, Hannover. gross.mechthild@mh-hannover.de
authors.forename: Mechthild M
authors.initials: MM
authors.lastname: Gross
authors.forename: Marc J N C
authors.initials: MJ
authors.lastname: Keirse
mesh_terms: D005260:Female; D006801:Humans; D007745:Labor Onset / Q000502:physiology*; D009774:Obstetrics / Q000379:methods; D011247:Pregnancy; D012107:Research Design