http://en.wikipedia.org/wiki/Demography_of_the_People%27s_Republic_of_China

We have met the enemy, and he is us — Pogo

Actually, I wasn't concerned with meeting an arbitrary ratio goal.  One child per couple is fine, but I was thinking more of long term, non-precipitous general population decline.  As long as the fertility rate is less than 2.0, population control is achievable in the long run.
I don't know if that's good enough in the short term.  Someone mentioned sustaining 14 billion as doable.  No thanks.  I'd like us (the world) to think about what the IDEAL human population on the planet might be and come up with a plan to achieve that over many years, with sensitive frequent re-evaluation, and respect for all cultures, races, nationalities, etc.  Nobody needs to get screwed.
But that's not going to happen.  The pope wants more catholic souls, the Muslims want more Islamic soldiers, etc etc.  Everyone will push for more than can be sustained.  Everyone will be looking for the exception to the rule (as in China).  And eventually (tomorrow, next year, next decade -- but not too long now) something's going to crack and world's guts are going to spill out.
And all our moralizing about abortion and compulsory family planning -- and maybe even global warming -- is going seem like a bad joke from the good ol' days.
I live in an under-populated country at the edge of the world, and you couldn't drag me back into thick of humanity with a whale harpoon -- present company excepted, of course.

Isn't the replacement rate 2.1?

you are the media you consume.