Dr. Harleen Frances Quinzel admitted to having a child 4 years prior, to a pregnant Black Canary, in the alternate universe comic Injustice: Gods Among Us: Year Two #13.
I typically only think of Harley in two universes, DC animated universe, and whatever DC is doing these days. New 52? Bah. This comic series, based around the fighting game Injustice, might be worth checking out. For more pictures, because it seems like all of the relevant comics have been spread on the internet by everyone, go here: http://imgur.com/gallery/fU8DI
Wow. The Joker, probably has a daughter. Hope he never finds out. I wonder if it’s going to be made canon in the main comics.