I went to thailand for my honeymoon at 18 weeks pregnant (we booked it about 5 weeks before i found out i was pregnant and couldn't get a refund. We decided to go anyway but upgraded our travel insurance). I was super careful about eating well cooked food from restaurants or the hotel only. Drank only bottled water and sealed drinks, no ice etc.
As for the plane we got seats right at front for the extra bit of leg room. Wear super comfy loose clothes for the flight too, makes a difference, it's so uncomfortable!!