No, it's not your imagination that your gums are more sensitive during pregnancy. Regardless what you do, your gums may seem to be bleed more when you're expecting. It's called pregnancy gingivitis, and it's caused by fluctuations in your hormone levels, which increase blood flow to your gums and other tissues. Pregnancy hormones also affect the body's normal response to bacteria, leaving you more susceptible to periodontal infections [source: American Pregnancy Association].
So what's a girl to do when faced with pregnancy gingivitis? First, see your dentist for an additional cleaning, and discuss any problems you might have. You also may want to consult with your OBGYN. Next, switch to a softer toothbrush, brush at least twice a day, and floss at least once a day. This won't avoid the problem altogether, but a bit of TLC with your gums during pregnancy will go a long way!