I'm wondering the same thing DIA uses this scanner that you step into and it rotates around your body. Is that what you have at your airport? I think I'm going to ask my doctor about it I have to go to Alaska at the end of the month. I looked it up on the TSA website and it was pretty vague.
I flew at 8/9 weeks pregnant. I would worry more about getting sick on the plane and where the bathrooms are in the airport. :)
When I flew back in June I was 25 and 27 weeks pregnant. Its safe to walk through the metal detectors (I was visibly pregnant but still mentioned and asked if it was okay)
I did get my belly ended up being pat down though, so don't be surprised if they do that lol. But besides that its all good!
I live on a military base and go through the metal detectors all the time for various events that our base holds and its perfectly safe!