A Woman's Brain Shrinks 5% While Pregnant

Perhaps I shouldn't have asked what Dan learned from his recently finished book, "The Expectant Father." I've googled my little heart out, and can consistently find "studies support a woman's brain shrinks 5% during pregnancy" but no one really explains why. So, of course, I was skeptical.
That was before I was welcomed by emails two days in a row upon arriving at work that my security badge was ready to be picked up in the lobby. Two days of two days this week I have managed to somehow, in the 10-15 steps it takes to get into the building from my extra special Expectant Mother parking spot, lose my security badge in the parking lot. Once, I could chalk off to accident. But, two?

Maybe the 5% has some merit... or else it's a nice break from my usual blonde excuse. I think I'll try it out.