I appreciate what you're trying to say, Sara, but in reality there is two obvious kinks to this system: Multiple children, and the damage your extended maternity leave will do to your career.
So you have a baby and decide to follow the "quit for 4 years, then return" plan. But two years later you give Sara Jr. [apropos to nothing, but why aren't female children ever called Mothersname Jr.? Why is it customary only to do this with male children?
] ... anyway, where was I, oh yes: you have a second child and suddenly your 4-year-plan is automatically extended to 6 or 7 years. That can go up to 9 or higher if you have a third kid, and so on.
BUT let's say you stick it out and, after the better part of a decade is history, decide to return to your career. But while you were patient enough to wait for your career, your career was not patient enough to wait for you. Everybody else has 7 (or whatever) years on you. Most of your old networking ties, ties with classmates, etc are history. You have to start from scratch. Plus, you yourself are going to be rusty, especially in a field like medicine which demands constant continuing education. Maybe you'll wind up like so many women and will settle for parttime / casual employment, or will give up and just not work at all.
There is no easy way around this. Stop kidding yourself. If it really were that simple, none of the posters here would have had stay-at-home moms, and this would never be a topic of conversation IRL.
Women in my class are constantly talking about this dilemma. A depressingly large fraction of them are going to quit when the kids come. Yes, I said "depressingly" because it's like taking all that long, expensive, useful-to-society medical education and *flushing it down the nearest toilet* while their husbands are making HALF of her potential income in a field such as marketing.
I may someday regret asking this but: Why don't women ever ask men to even *consider* making this kind of sacrifice instead? Especially when logic is overwhelmingly in her favor, i.e. she is an M.D. and he is a college dropout?
Why don't I ever hear the other guys wondering what will happen to their careers when the baby arrives?
Conversation you will not hear at the local sports bar:
"Oh, I just don't know how I will be able to finish my residency once my wife gets pregnant. Their paternity leave sucks, and you just know they'll daddy-track me even if I do come back to work."
"Yeah, I hear you man. My wife is already demanding that I stay home, at least for a few years. She's a schoolteacher and I'm an orthopedic surgeon but you know, she has a point because dads in her family always stay home with the kids."
"Maybe you should. My wife and I tried working full-time but it just wasn't doable even with daycare. So I had to sell my practice to stay home. But who knows, once we're finally done making babies, maybe I can work part-time at a doc-in-the-box! <crosses fingers> Ooh, and the Buckeyes just scored a TD, yesss!"
anyway, uh... um yeah.