I thought they were built for that. For tens of thousands of years women had on average 7 children or more, it looks like the process is very reliable. These days birth-giving mortality is very close to zero, also post-birth care is quite good, so we are in a better place than ever and still concerned?
https://www.reddit.com/r/TwoXChromosomes/comments/1t6akt4/id...
Just because women used to birth 7 kids with high morbidity and mortality rates does not mean they wanted to.
Mortality aside, pregnancy is incredibly hard on the human body. Demineralized bones, anemia, vaginal scarring and fistulas, etc etc. Whole lot of stuff can wreck your body without killing you.
Also reliable and affordable DNA testing makes much easier collecting pensions from fathers that before would just vanish, or outright deny paternity. An underrated breakthrough in women and children rights enforcement.
Societally, almost everyone would argue we shouldn't encourage women to have kids that young.
For example, in Tudor England, women generally got married in their early 20s and men on their late 20s. People absolutely knew pregnancy was dangerous for girls who weren't full grown.