150 years ago women regularly had kids in their 40’s. They had kids till the kids just stopped showing up.
Having kids in your 40’s is definitely not a new thing. Look up your own family tree if you don’t believe me. It was quite common, especially in rural families for women to have kids beginning in their mid/late teens every 18m-2y until they were in their mid 40’s.
Having your first child in your 40’s is a new thing. You’re correct about women continuing to have children into the 40’s but most of them started in their teens and 20’s. Women who did not have children by the time they were thirty to forty were considered barren if married and old maids if single.
True, but the key metric is age at first pregnancy-to-term, not age at last. On that basis there has been a dramatic shift over the past century.