The one thing nobody thinks about in delaying Child Birth is being Grandparents.
If you have a kid at 25 and your kid has a kid at 25 you are a grandparent at 50. Still young and have energy enough to be in a big part of your grandkid's lives (and have fun!). You will also likely live to be a Great-Grandparent.
If 35 & 35 then you are a grandparent at 70, you are old. While you can still enjoy you grandkids when they are little, you likely won't be alive and/or functioning in their teens & early 20's
Very true.
My own case is worse than your illustration. I have six children but ... it is a “yours, mine, and ours” family. Remember the old Hollywood joke, “Honey come quick, your children and my children are beating up our children.” My first wife produced two children. My present and final wife has brought forth four children. So the average fertility rate of my mates is three children per woman. But my youngest child is only nine years old. My wife was 37 and I was 58 when my youngest was born. Those long generations mean we are falling further behind as a percentage of the population than the typical 1.7 child per woman American/European White birthrate would indicate.