This fall in births has been a fact fro some time. Just like Japan and much of Europe, much of the population is taking a pass on large families.
You can point to-alarmist “climate doom” propaganda, the ZPG folks - who are still very active - and the current tax structure.
Bottom line, small families, if folks have any children at all....
Not all gloom and doom - with automation growing into society daily, fewer people are needed to maintain a working economy.
It’s all good until the remaining citizen get buried under a wave of illegals.
We need stable families to have 3 kids for continued growth. Not happening.
Also, consider that prior to WW2, ~80% of Americans lived on farms. We had large families because that was our work force.
After the war, returning vets eschewed the farm to work in the factories that had expanded for the war effort. They lived in ~1,200 sq ft tract homes on ~1/8 acre lots and didn't need lots of kids to maintain the property.
They raised self-absorbed, self-centered children, many of whom eschewed having any kids of their own.
I remember a popular acronym in the 80s: "DINKS." "Double income, no kids."
if you want your culture and your values to exist, a population must produce children......