A few of the last vehicles i had used the ignition/door key to turn on/off. The pregnant wife doesn't like it on when riding shot gun. At least while the lil one is still cooking.

Just one of those things that you hear about over and over. No worries though. Thanks
As Jeepjeepster said, it's automatic. There is a sensor in the seat that detects when *something* is on the seat, but that something isn't heavy enough... ie, a small child.
However, I have to add that I'm not sure why she'd be nervous about this. The NHTSA is 'reviewing' the issue, but from a standpoint of logic, assuming she's a full sized passenger, this shouldn't be an issue. For instance, the airbag would probably be better than her pregnant self slamming against the dashboard or worse, flying through the windshield. Also, there's evidence she'll take more damage from the seatbelt than the airbag. It's recommended that women who are pregnant don't cross their abdomen with the belt, if possible. Ie, put the shoulder portion over the collarbone as high up as possible, and the lap portion of the belt under the abdomen.
It was found that airbags were dangerous for children because they deployed at their heads, causing their necks to snap back resulting in injury. I believe the NHTSA has merely recommended sitting as far back from the airbag as possible, but hasn't declared that they're dangerous (or more dangerous than slamming into the dashboard, steering column or my favorite: flying through the windshield).