Fertility peaked in the U.S. in 2007, just before the recession, at 69.7 babies per 1000 women. Last year it dropped to 64.7.
The CNN report I cite for these figures cheerfully opines that "we aren't going to run out of people soon." However, we could start to run out of people, especially young workers, in we do not have enough babies now. The U.S. is probably OK, but all other industrialized nations are showing similar fertility drops with the recession, and they were in a deep population-trend hole to begin with.
If we want 20 year olds twenty years from now, we have to have them now. By then it will be too late.