Controlling for age would bias the sample.

Here's an a pair of articles on the mental model called inversion, which is about avoiding stupidity. [2] [3]

An example of inversion "If going down Route A in the dark in the rain is correlated with traffic accidents, take Route B, regardless of the fact that one's super tires or eagle eyesight might supposedly negate causation."

The same reality holds up at scale, and not just at the one university clinic, but they retracted it for political reasons. [4]

That is a very serious math situation if one wants more babies. Most parents would simply tell the young driver to stay off Route A in the dark or rain.

I did misread the ages between the two, and I have removed the age references.

2. https://fs.blog/inversion/

3. https://www.theengineeringmanager.com/growth/invert-always-i...

4. https://pubmed.ncbi.nlm.nih.gov/29889622/