Talk to your Dr, I asked mine the same thing. She told me that under no circumstances should I start a new, high intensity workout routine while I was pregnant,
especially running. The reasons were that when you start a new, high intensity workout routine you will end up depriving the baby of oxygen. And, the tendons that hold your uterus in place can stretch and even break away with that much bouncing action.
All in all, I'd wait. My 2 cents.