Extreme premature child's long-term prognostic is getting better and better known, and if a resuscitation procedure is possible at birth, it won't guarantee survival or a survival free of disability. Incertitude toward individual prognosis and outcome for those childs remains considerable. In this field, we are at the frontier of medical knowledge and the answer to the question, "how to decide the ante and postnatal care?" is crucial. This work is focused on this problematic of decision making in the context of extreme prematurity. It attempts to deconstruct this concept and to explicit its stakes. Thus, with the support of the medical sources and of philosophical debates, we tried to build a decision-making procedure that complies with the ethical requirements of medical care, accuracy, justice and equity. This decision-making procedure is primarily concerned with the singularity of each decision situation and it intends to link it closely to the notions of rationality and responsibility.