What is claimed is the ornamental design for a baby sleeping bag, as shown and described.
FIG. 1 is a perspective view of a baby sleeping bag, illustrated as worn by a baby, showing the new design;
FIG. 2 is a front elevational view thereof, illustrated as laid flat;
FIG. 3 is a rear elevational view thereof, illustrated as laid flat;
FIG. 4 is a left-side elevational view thereof, illustrated as laid flat, the right-side elevational view being a mirror image thereof;
FIG. 5 is a top plan view thereof, illustrated as laid flat;
FIG. 6 is a bottom plan view thereof, illustrated as laid flat; and,
FIG. 7 is an alternate perspective view thereof, illustrated in an open configuration.
The broken lines in FIG. 1 showing a baby are included to show the invention in use, and form no part of the claimed design. The remaining broken lines in FIGS. 1 and 4-7 represent stitching, and are part of the claimed design.