We're losing our fertility edge:

For years, America was unusual among rich countries in having a relatively high [total fertility rate] of around 2.1, the so-called “replacement rate”, at which a population stabilises over the long term. European countries were typically below that rate, sometimes far below it. So it comes as something of a shock to discover that in 2011 America’s fertility rate was below replacement level and below that of some large European countries. The American rate is now 1.9 and falling. France’s is 2.0 and stable. The rate in England is 2.0 and rising slightly.