Who is wife of John Crawford, born 1746, SC?

For years, I have been told that the wife of John Crawford, born 1746 was Lucy Ann Moorman. All trees I have seen, has her down as born 1729. This would make her 17 years older than John. This would make Lucy 41 years when she had Elizabeth and 44 when she had Mary. Both Elizabeth and Mary (Polly) Crawford married Ellerbe Brothers. I am sorry, but I think this imformation is incorrect. I do not think a woman of the 1700's would be 17 years older than her husband. It just was not done back then. And being in her 40's in childbirth would kill her back then, that is too old to have a child.
I really would like someone who has some serious information on the wife of John Crawford and the mother of Elizabeth and Mary to come forward with some information and proof.