An absorbent structure designed for use in absorbent pads such as diapers is disclosed. According to a first aspect of the invention, absorbent pads are provided which comprise at least two layers of cellulosic fibers (fluff) of different densities or average pore size ranges. When the absorbent structure is incorporated in a diaper, the lower density element extends to the full length and width dimensions of the normal absorbent component of the diaper. The higher density element lies beneath at least a portion of the lower density element. According to various embodiments of the present invention, it can run as a strip from the target zone to the back waist of a diaper, it can run along a central portion extending the whole length of the diaper, or it can underlie the entirety of the lower density element. The higher density element (or the element having a lower average pore size) wicks waste fluid from a lower central portion of the diaper, and thereby transports the fluid upwardly and also transfers it to the lower density element (or the element of greater average pore size). According to a second aspect of the invention, which may be incorporated with the first aspect just described, a portion of superabsorbent material is placed beneath the higher density layer, (or layer of lower average pore size), such that an additional reservoir for absorbing waste fluid is provided.