vjc,
As you have read in all the replies diethylene glycol is not used in e-cigs only propylene glycol which is FDA certified as a food and drug additive. If you read the labels on a lot of over the counter meds, skin and hair products not to mention suppositories you will find propylene glycol all over the place.
As much as I hate to post subjective caveats the state of California does have a warning about nicotine use by pregnant women. As far as I know California is the only state that has such a warning.
PS - don't tell your wife about the Nicotine caveat until you have researched it to your satisfaction. Also if you are concerned one nice thing about e-
juice is you can reduce the nicotine content to the point that is just enough to keep the Monkey off her back and minimize any possible harm to your child (assuming she can't just cold turkey off nicotine, like most of us).