At least in the midwest, we have had a record-high number of kids for the last 10 years or so (so many more kids that new schools keep being built to try to keep up with it because each new year the number of enrolled kindergarteners is higher than prior, daycare facilities have a minimum 1 year waiting list and many are closer to 2 years, summer camps sell out entirely in minutes, etc)
I think people hear "low fertility rate" and just assume this means "adults aren't becoming parents" or "not enough kids being born".
But if you spend 5 minutes on the ground, it becomes immediately apparent that we have the opposite problem -- there's so many more kids being born and raised than before, and most of our municipal/regional support systems for parents and children have not yet expanded to accommodate the slow-surge in births.