The ornamental design for modular maternity mattress system unit, as shown and described.
FIG. 1 is a front elevational view of the main mattress of the modular
maternity mattress system unit embodiment of the present invention,
illustrating the central opening thereof with the two modular plugs
removed therefrom, such view being the identical view as the back
elevational view thereof;
FIG. 2 is a right side elevational view of the main mattress of the
embodiment thereof as in FIG. 1, such view being the same as the left side
elevational view thereof;
FIG. 3 is a top elevational view of the main mattress of the embodiment
thereof as in FIG. 1, such view being the same as the bottom elevational
view thereof; and,
FIG. 4 is a generally front and top perspective view with partial right
side perspective view of the main mattress of the embodiment thereof of
FIG. 1, with the two modular plugs of the modular maternity mattress
system unit positioned in exploded view relative to the main mattress
central opening therefor, it being understood that the tops and bottoms of
such plugs are flat and unadorned, and the curved peripheries thereof are
smooth and unadorned with a curvature to mate with the main mattress
central opening; and,
FIG. 5 is a front elevational view of the main mattress of the embodiment
thereof as in FIG. 1 with the two modular plugs of present FIG. 4 received
in the central opening thereof as shown by the broken line explosion line
of present FIG. 4.