IMHO we're straining at gnats here. Given that Cawti is in the
simultaneous throes of a revolution and an ugly divorce, it'd be
quite easy to miss the fact that your were pregnant for quite a
while. 'Skill and ability to percieve' is often trumped by 'not
paying attention.' And even if she did notice or simply suspect,
she might have decided to keep some of her options private by not
telling him.
Bear in mind, too, that first pregnancies can be a lot less obvious,
both to the person who's preganant and the outside observer. Given
the time scale, Cawti could easily be 3-4 months pregnant by the
time Vlad takes off with neither of them having noticed.
Occams razor, yadda, yadda.
--
"There's a lot of my personality in my characters. I think that's why
smart-asses are over-represented."
Christopher Moore, in http://www.chrismoore.com/world_domination.htm