The invention relates to a prosthesis for supporting a breast implant comprising: a reinforcement part configured to receive a curved lower portion of a breast implant, the reinforcement part having an elongation under 50N in the vertical direction of E1, a fixation part intended to be fixed to the pectoral muscle, the fixation part having an elongation under 50N in the vertical direction of E2, and a transition part connecting together the reinforcement part and the fixation part, said transition part having an elongation under 50N in the vertical direction of E3, wherein E3 is greater than E1 and greater than E2.