[WarOnPrivacy]

> a lot of the fertility decline is the result of less unplanned pregnancy. Teenager's are far less likely to give birth.

I do genealogy and have created 10s of 1000s of profiles, mostly of people in the US from 1850-1950. Much of what I see aligns with common knowledge of historical birth rates and parenting stats.

But not everything. One exception is that (Adult-Reaching) First-Born kids of moms <18 is a significantly smaller demographic than I would have expected. Families that start with moms in early-mid-late 20s are all better represented.

This isn't to throw shade on common knowledge. I suspect our CK is missing some nuances in the data (data from the groups I work on).

  To give another example of missing nuance: We know historical lifespan averages were strongly shaped by infant mortality but they were also shaped by labor-related deaths (ex:black lung).