The third generation of the regional healthcare organization plan (Sros III) proposes to develop the organisation of healthcare and its management according to evolution of its activities and the populations concerned. At the time of a strategic analysis of SROS III (what we refer to as its perinatal period), the question is whether promoters can move from an approach based on accessibility (egalitarian equity) to a needs-based approach (differential equity), which although more complicated in to apply and implement, was found be much better adapted to healthcare users. The research is derived from an analysis of documents from November 2004 to November 2006. A university public hospital developed the data which supported a proposal to shift from level I to level II. This proposition was retained in the territory's medical plan authorized by the regional health authorities. Health professionals and the architects of the healthcare plan have the capacity to new organizations responsible for taking into account the activities and healthcare needs of the population in order to initiate and establish differential equity.