Herpes type 1

I've had herpes for over 2 years and I've ever had only one outbreak over those 2 years.
However, I'm 14 weeks pregnant now and within those 14 weeks I've had 2 outbreaks  (currently just got my second one). Does any women know why I've gotten more outbreaks since being pregnant? Also, is valtrex safe during pregnancy? My doctor knows i take it, and doesn't seem to have a problem however I still seem to be a bit paranoid. 
Is anybody familiar with this? Any help would be appreciated