I claim the ornamental design for a baby UV sterilizer, as shown and described.
FIG. 1 is a Perspective view of a baby UV sterilizer showing my new design;
FIG. 2 is a Front view thereof;
FIG. 3 is a Back view thereof;
FIG. 4 is a Right-side view thereof;
FIG. 5 is a Left-side view thereof;
FIG. 6 is a Top view thereof;
FIG. 7 is a Bottom view thereof; and,
FIG. 8 is Other perspective view thereof.
The broken lines illustrate portions of the baby UV sterilizer that form no part of the claimed design; the broken lines form no part of the claimed design.