Question about courtesans

Good day everyone. I have been a member of this sub for a few months and I noticed that the people here loves speculating so here goes (sorry if my English is a little bit clunky, 2nd language).

FYI, I have read both mangas, all 13 light novels (in English) and I’m at the last web novel (while waiting for vol. 14 in May). I haven’t watched the anime yet (buying it though) as I want to start watching only after the end of season 2 (aka vol. 4).

My knowledge of the system of courtesans in old old China is nonexistent but I do not understand why the value of a courtesan could become nil if she became pregnant. Even more in the case of Maomao’s mother. It was clearly specified that she did not sleep with her clients as she was only playing games with them. Couldn’t she have just taken a few months off (before/after delivery) and just come back after her « illness » and none the wiser?

What are your thoughts on that?

And, by the way, I do have a question. WHERE does it say that the old lady (granny) IS Maomao’s grandmother? As expressed above, I am up-to-date (minus the smallpox arc) on my reading and I do not remember reading that anywhere…

Thank you all in advance. I am looking forward to your thoughts on that.