WARNING: THIS ANSWER MAY RUFFLE SOME FEATHERS
I'm not a doctor, but common sense tells me that the amount of nicotine that might be on your lips or hands is meaningless.
So that part I wouldn't worry about any more than I worry about getting a bit on my own hands or lips.
As far as what is exhaled, it depends on how much nicotine there is in exhaled vapor.
The fact is, we really don't know, but all studies point to there not being enough to be harmful.
Let's put it this way, if it were me, until we have more information I would not
chain vape around my pregnant wife.
But I wouldn't go running outside every time I want to vape either.
And I wouldn't even give a second thought to having a puff or two here and there with her around either.
But that's me, and I wouldn't even make my poor kid wear a stupid bicycle helmet either.
I'm thinking if you really want to be as safe as humanly possible, don't let her drive anymore.
And that includes before the baby is born, and after as well.
But in my opinion, anyone telling you not to vape around your pregnant wife should also be supporting vaping bans indoors.
And I doubt many of the people that have responded here would support such a ban.