I suppose the answer to setback dice would be, it depends. If your PC is going to be pregnant for more than a couple sessions, giving her a setback die for every Brawn/Agility related skill would get old, FAST.
Secondly, this is Star Wars. IMO, it's not a setting where you should need to simulate pregnancy difficulties and complications due to wounds. So…unless a player wants his or her character to have a miscarriage, I would never be douchy enough of a GM to cause a miscarriage due to a critical hit. Especially since in this system wounds and critical hits can be rendered in a wide variety of narrative ways.
I will add, though, that there was a discussion about this on the Order 66 podcast for Saga Edition, and if I remember correctly an interesting suggestion was some negative modifier (probably -2) to all Dexterity-related skills but the pregnant woman gets the Rage species trait, as per Wookiees. So that might be kinda cool :-D Basically add a setback die to any Agility check if she's in her third trimester, but give her the Wookiee rage ability.
And if she's already a Wookiee….I dunno. Give her double-rage
But seriously, don't even touch the miscarriage part unless the player wants that to be part of the story. That's my two wupiupi.
EDIT: lol, Sturn