What we need is a 1 child policy like in China.
Because it's demonstrably successful at curbing population growth rate? Because during periods of the most aggressive enforcement of the one-child policy, China had its highest growth rate in recent history, 2-2.5x that of the US?
And now, during its period of least aggressive enforcement, but with a rapid pace of industrialization and wealth injection, the growth rate has fallen dramatically?
http://www.indexmundi.com/g/g.aspx?v=24&c=ja&l=en
Or perhaps we want to look at Japan, which without forced abortions, property confiscation, and brutal acts of repression have managed to achieve a negative growth rate?
No matter which way you slice the data, the trend is clear: industrialization, wealth, and stability decrease growth rates, and do so far better than any number of guns and Bibles you can point at people.
The fact that China would think to enforce such a policy should give one pause.
Look at Japan where there are fewer and fewer supporting more and more. It is kinda working for now but what will happen in 20 years? Who knows.