*SPOILER WARNING*

So that scene where the joker is waiting to hear news about harley from his henchman, it shows that he had spent time arranging weapons around his body while he waited like the crazy and heartbroken man he is. When the camera zooms out, at the very edge of his circle, you see baby paraphernalia - little onesies and whatnot. Which I thought was a little odd, because wtf would the joker have baby clothes just lying around for? Why would he bring them out when he was obviously worried about harley?

Then later on in the movie, when enchantress is showing suicide squad visions of the things they want most out of life, harley sees herself married to the joker with two kids, as a normal couple. Now at this point in the film, she thinks the joker is dead and that she’s alone in the world, so she knows this can’t happen. But notheless, she wants this life with him.

So the thing is, when both of them are alone, severely missing and thinking about the other, the idea of jorley babies is hinted at in both scenes. Which makes think that they either talked about it, or it was something that they both wanted in relation to the other. Either way, it shows harley’s longing for something normal and the joker’s willingness to give it to her. Which, to me, makes his line “I’ll do anything for you” all the sweeter.