Originally Posted by
LegalTender
Likely you can board early, but there's nothing in writing. Can't sit in exit rows.
Flying While Pregnant
My (then 7 month) pregnant wife and I just flew from the east coast to Hawaii and scored the double exit row seats on literally every flight with never an eye batted from the FAs. We didn't have to "preboard" though so if you need to do that, preboards are judged to not be capable of helping during an emergency.