Disposable absorbent article comprising expandable fibers and being capable of self-shaping in use

A sanitary napkin to be worn by a female user adjacent to her pudendal region, the sanitary napkin having a longitudinal centerline and a lateral centerline orthogonal thereto and defining longitudinal and lateral directions, respectively, the sanitary napkin further having a Z-direction which is orthogonal to both the longitudinal and the lateral directions, the sanitary napkin further comprising a liquid pervious topsheet, a backsheet joined to the topsheet, and an absorbent core intermediate the topsheet and the backsheet, the absorbent core comprising a body faceable surface, the sanitary napkin being substantially flat prior to use, wherein the absorbent core comprises a layer of compressed, regenerated cellulose, linear fibers capable of expanding the sanitary napkin into a tridimensional structure while being worn by the user and having a dry density of from 0.1 g/cc to 0.4 g/cc, the expanding layer of compressed, cellulose, linear fibers having a thickness of between 2 mm to 7 mm, and the expanding layer of compressed, cellulose, linear fibers being activateable by body fluids from the female user.