My great grandmother had her 13th child at age 49. Her husband died shortly afterwards so that was the end of that. Her daughter had a “surprise” pregnancy (my Dad) at age 50. Stranger things do occur; however, this was during the time period when birth control was limited. The same gossip about a White House baby floated around when Bill and Hillary occupied it. Not cred IMHO.
Many years ago they were called “Change of life babies”.