Patented is a sanitary napkin to be worn by a female user adjacent to her pudendal region. The sanitary napkin has a longitudinal centerline and an orthogonally located lateral centerline, which make up longitudinal and lateral directions, respectively. The sanitary napkin also has a Z-direction, which is orthogonal to both the longitudinal and the lateral directions. The sanitary napkin further comprises a liquid pervious topsheet, a backsheet joined to the topsheet and an absorbent core intermediate the topsheet and the backsheet. The absorbent core comprises a body faceable surface. The sanitary napkin is 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. It has a dry density of 0.1-0.4 g/cc. The expanding layer of compressed, cellulose, linear fibers has a thickness of 2-7 mm and the expanding layer of compressed, cellulose, linear fibers is activateable by body fluids from the female user.