Abstract: An improved maternity mattress has a recess formed therein which accommodates a woman's expanding abdomen as a pregnancy progresses. The recess may be filled in by a plurality of stackable pads with each pad having approximately the same thickness. A sliding cover sized to allow for selectively covering and uncovering the hole is preferably controlled by an electrically powered mechanism, and may also be used to vary the diameter of the opening to the cavity. A control panel having switches for operating the sliding cover is preferably made of an expandable, flexible electrically insulating material such as rubber. A locking mechanism is provided to insure that the sliding cover remains closed.