Tim Pratt, author of one of the best damn sf short stories I've ever read (and if you haven't read it yet why haven't you?), has an essay up on Clarkesworld about juggling baby duties and writing:
With a kid, long chunks of time to write is like perpetual motion or zero point energy. You just can't get it, at least, not without putting more energy into the system than you get out. I was seriously contemplating hiring a babysitter for a few hours just so I could write — but with the kind of money fiction writing pays, that quickly becomes a losing proposition, economically speaking. So... I adjusted. Turns out, that's what being a parent requires. Yes, I'm a natural binge writer. Yes, my preferred technique is to slip into that wonderful zen state of flow for several hours and emerge with twenty or thirty pages of prose. But you know what? Too bad.