If couples are not having children, nobody is going to stop them.
Americans need not have children! We can replace our people with illegal aliens. We need no population, we can use robots and Mercenaries to fight for us. Why have children? They cost too much, take valuable time from young adults having fun. But, we better watch out—As Rome discovered when the Germanic People moved in—in time they will take over and usher in a new Dark Age. This time it will be followers of Mohammed and Allah.