Alessandra doesnt care about power so telling her that about a baby would do nothing for her. She likes staying behind the scenes and being a puppetmaster.
1) We don't even know for sure that she doesn't want to be in charge. She says she doesn't, but she's not exactly an honest person and she also says this:
and then in front of her sisters, really seems to milk the idea that she has absolutely no goals besides endless hedonism
It's very possible that she
does want to be in charge, she is just hiding it while secretly building allies with the ladies of New Paris and pitting her own sisters against one another. Considering the fact that Dominique and Juliette are teaming up against Olivia, it would sense for her to keep her ambition hidden. According to the faction sheet though, she can never win the Gambit which seems to disprove this a bit. However, she can still become the leader of World State C, meaning she is willing to become the leader to protect her way of life if her back is pushed up against the wall.
2) More importantly though, not wanting to be the leader and not caring about power are definitely not the same things. After all, she has been pitting her sisters against one another (or at least been trying to) and been trying to get Olivia in charge. She very much cares about
who is in power. To expand on this, her child eventually being in charge would likely be something that she would like. Why wouldn't she want that? And if Kane told her she's either off the board,
or has to give him a child and have that child participate in the gambit... well, I definitely don't think she would give up her position on the board. And besides, as much as she goes on and on about female supremacy she seems to like being fucked by a dominant Kane.
If anything, she would work to get her chosen leader pregnant.
Well, if what she's been saying is true, then that's exactly what she's been doing with Olivia. But her plans might have to change if evil Kane manages to get his way is what I'm saying...