In this article, we propose to study the discourse contribution of enumerative structures involving the prepositional phrase pour deux raisons. We would like to highlight the contribution of the textual information conveyed by enumerative structures and the prepositional phrase both to the discourse structure and the discourse content within the SDRT model. We will show that prepositional phrase like pour deux raisons must introduce a discourse constituent in the structure attached by the Commentary relation to the left context and the Enumeration relation to the right context. Finally we propose to treat pour deux raisons as a new kind of discourse marker: we will show that its discursive role within enumerative structures is to signal the content-level relation Explanation.