Callie has A positive blood type.

Alex: She works here at Seattle Grace Mercy Death, so I’m sure she’s pretty much gonna go crazy or get cancer, shot by a gunman or hit by a truck. So, don’t get your hopes up for Karev’s big happily ever after.

Meredith: Yesterday at that baby shower, I was jealous of Callie because she got pregnant without trying. And we tried. I get shots, I take my temperature, I put my legs in the air, and nothing. The universe says screw you Meredith and gives Callie a kid. And then puts Callie through a windshield. I mean, what the hell is going on? What's the point? I mean, is there a reason for this? Because if you can think of a reason, any reason at all why the universe is so screwed up. And random. And mean. Now would be an amazingly good time to tell me because I really need some answers.