I've made lots of charity quilts.
Size: many quilters make small (uses 1 width of fabric for the back). So I make lap size and up. I can usually find 5-6 yards from my stash that go together for whatever size that makes. rectangular are preferred over square
Gender: male needed.
There's a great childrens hospital in our area. The NICU requests basinette covers to block out the light onto the preme. They gave us dimensions and colors. They use sterilization techniques on them and keep them for the next infant.
Check with the group receiving your donations. Each makes there own desires list.