A mattress (10) comprises a support base (12) defining an interface surface (14) at the top thereof and a softer compressible layer (22) overlying the interface surface. The thickness of the support base varies along a longitudinal direction such that the interface surface (14) defines a concave laterally extending channel between first and second support surfaces (16,20) for the upper and lower halves of a user's body respectively, and the compressible layer (22) substantially follows the profile of the interface surface (14). The mattress (10) is particularly useful for a pregnant woman who can comfortably lie on her back, side or front.