It's... weird that suddenly now he has to have something between him and and the baby, when he didn't before. He could probably draw the right conclusion if he took a minute to think about it, but he's too distracted with getting to hold her again and being excited about that to consider much else.

He does as he's told, cradling her head, bracing her against his body. He's awkward at first until he gets the rhythm of how to hold and pat her at the same time. She fusses and squirms, and he's just about to ask if he needs to do something different when she lets out a big burp.

And then she spits up all over his shoulder.

Jim pauses long enough to make sure the baby's okay before he looks up at McCoy. "Bones, goddam-- uh, gosh... crap. Did you know that was going to happen?"