I personally wouldn't risk it.
Just because you never know what could happen.
Plus I don't know if the company would allow you
It could be a liability.
Personally I'd go at 11 weeks baby is still so tiny and cushioned. But if also speak to the hot airballoon agency as they may advise against it. X
I will only be 11 weeks :)
No although I've been in two hot air balloons while on holiday in Egypt i wasn't pregnant. Depending on how far you are I'd check with the agency if it's ok, because of crash landings etc... If I was before say 16/18 weeks I'd probably do it, baby is cushioned and the crash landing we had was actually fun :) but always enquired x