Abstract: A maternity mattress which provides a cavity for accommodating the protruding abdomen of a pregnant woman as she lies in a frontally downward position upon the mattress surface. The invention includes a multi-chambered inflatable vessel centrally positioned in a mattress which forms a flat, elastic mattress surface when fully inflated which can form a cavity for supporting a pregnant woman's abdomen by adjusting the degree of inflation of the individual chambers of the inflatable vessel to allow the elastic top surface of the inflatable vessel to adapt to the configuration of the pregnant woman's protruding abdomen.