Speaking as the female half of a couple...leave stuff around for her to read (like Boston's book? I haven't read it but it might do nicely). Ease into it slowly. Answer questions and talk about things as they come up - as SHE brings them up.
I guarantee you there is an excellent chance that she, too, is feeling a little uneasy and uncertain about what the future holds! A recent poll said 65% of those in the U.S. are expecting some sort of catastrophe to happen and only 10-15% thought they were ready for it.
Re: easing into it....She'd probably be open to the idea of stocking up on staples when they are on sale, if for no other reason, to let her have the freedom to rest up and enjoy the new baby rather than having to make trips to the store all the time!
She might be willing to consider renewable infant items, rather than disposable ones. I found that "old" diapers from the diaper service were completely serviceable, lasting through two kids of my own, incredibly absorbant, and better quality but cheaper than those in the stores. I only bought disposables for when they'd be at (for example) the church nursery. Washable nursing pads were nicer, too, than the disposables. Cloth is just kinder to skin than paper!
Renewable items, of course, take a little more effort to clean and reuse - but not much more effort than a trip to the store and hauling out the trash. And they are certainly kinder on the wallet!
Not to mention that nursing a baby is essentially "free" (the mom might eat a tad more), and a lot more hassle-free and healthier than going the formula route!
These habits also get you used to being in a mindset of "how would I do this if I couldn't run down to the corner store to just pick something up?"
Read a lot. There are a lot of good blogs out there, and some very good apocalyptic fiction is being published right now. Much of it is of the free/.99/1.99 variety in e-book format - and there are programs allowing you to read e-books on the computer, so you don't even need a Nook or a Kindle.
Finally, the goal you will have is obvious: a safer place for her and the baby, and a safer place for your child (or children) to grow up. At the heart of it, this is something she wants, too. Remember that.
My significant other found a blog entry somewhere about "how to get your spouse to go along with your prepper ideas" or something like that. It had some good ideas...although, unknown to him, I'd had almost a year's supply of food and a bunch of water, along with emergency shelter (tent), first aid, clothing, and shoes, nearly two decades ago - long before I met him. For me, this is largely just returning to the level of "prep" I had before, ramped up a bit, with the idea of adding some more useful items and skills. I didn't take much convincing.
