Can you help me understand why a 45 year old woman with 19 kids already, who has previously had two miscarriages, would want to continue getting pregnant?

I heard today on the news that the Duggar family’s mother just had a miscarriage. She is 45 and has had 19 children already. She apparently wants to get pregnant again. She already had two miscarriages (this one and one last year or two years ago).

I don’t watch this show so I don’t know anything about the family, other than the little that I have heard from the news, which is that they have all these kids. I do totally understand the desire for some people to have large families. I have one child and if I were younger and able to have more, I would be totally willing. However, I don’t understand why someone who already has 19 kids would want to get pregnant again.

Can you please help me understand? Am I missing something?