This is MUCH better than the Medela sleep bra because the elastic band is thicker and therefore grants more support. I don't know if you should size up, what I felt was too small was the elastic band, I'm a 36 and bought L which should fit but it felt snug and suited to a 34 size I had trouble pulling the bra over my head to wear it. Next the shape is weird the shoulder straps are too wide there's way too much unnecessary material under the arm and on the top of the chest. Otherwise the cups seem true to size. Material is almost sheer, very thin cotton, and nursing pads will show up clearly under the bra.