Dog eating underwear since I became pregnant

Question
Our 8 year old bordie collie mix has always been VERY well behaved. She's very intelligent and gets a lot of special attention from my husband and I. However, she's also very much my dog and prefers to be with me. In our home we have 1 other dog and 1 cat. We've never had any behavior issues out of her and she's never chewed previously.
I am 6 months pregnant with my first child and our dog has just begun chewing the crotch out of my underwear. She's also chewed the crotch out of pants that I own. This behavior is getting more frequent. Recently, she opened the closet and pulled out several items from the hamper. She didn't destroy anything else she pulled out of the hamper (t-shirts, pants, my husband's boxers). She took 2 pair of my underwear and destroyed the crotch.
When I get home, she'll be very upset- as though she knows that she misbehaved. I've made a point to continue doing special activities with her (taking her alone for car rides, park time etc).
Do you think she can sense the pregnancy? Could she be upset with me about something or feeling territorial? I'm concerned that this is a bad indication for when the baby arrives.
I appreciate any help you may provide. I love our very much dog and want the upcoming transition to be smooth.

Answer
Dogs are very sensitive to scent, and this is probably just a case of your scent having changed.  I would not worry about dominance or territoriality in a dog that has never displayed that before.  If you think she's looking guilty, that has more to do with your demeanor when you find the chewed object (try really hard to limit her access to underthings and IGNORE any mistakes she makes - that way she will have no reason to seek attention by doing it and it will hopefully go away once baby is born).  For reliable information about dogs and babies, go to the Dogs & Storks web page or attend one of their presenters' events.  Also, there's a great book by Coleen Pelar on raising kids around dogs.