The predictors for needing a lift are: a) the volume of the implant; b) the plane of implantation (subpectoral or subglandular); c) the position of your nipple; d) the elasticity of your skin brassiere. Given your situation, I think that it is doubtful that you will require a lift when you downsize.
With respect to the implant you should target, choose one whose base diameter is slightly more narrow than the one you currently have. good luck.





