In most of human history it would be even younger.
Although most of this first children would not survive.
It was in most of history said that the first two children were for the crows.
My grandmother’s first, third and forth pregnancies were stillborn or died in infancy.
“In 1800, the American birthrate was higher than the birthrate in any European nation. The typical American woman bore an average of 7 children. She had her first child around the age of 23 and proceeded to bear children at two-year intervals until her early 40s.”
https://www.digitalhistory.uh.edu/topic_display.cfm?tcid=134#:~:text=In%201800%2C%20the%20American%20birthrate,intervals%20until%20her%20early%2040s.
This is an urban myth that presumes previous generations and cultures were stupid and didn’t realize that early marriage and childbirth were associated with maternal and infant death.
Average age of first marriage for women in colonial America was 20-22. In Tudor England it was 24!