I'd love for you to add your tips for freelancer moms in the comments. For instance, what do you do if you run an online business for which you handle the shipping? What about it you own a store and you're in charge of keeping the books?
Has anyone hired an interim replacement, or farmed work out temporarily to associates or friends?
1.) Keep in touch with clients, and keep reminding them exactly when you'll return to work fulltime, if that's part of your plan.
2.) Plan to hire a mother's helper a few hours a week, so that you can spend a little time with your work.
I've just started some freelance work on the side, so it's interesting for me to explore this topic, but my 8-hour days take place in an office. I'm lucky that my company is required to hand me 12-weeks away from my desk for maternity leave, and promise that the paycheck will still be there when I return. It's not that cut-and-dried for entrepreneurs, I know. But do it somehow, for you. Ultimately I believe the health of your business depends on your turning it off for at least a little while.
Next up, I'll tell you why you should stay in touch with your office while you're on maternity leave (even though you reeeally don't want to).