Not just butt in the air but also then stretching out on left side, left leg and arm straight out above and below, right arm and leg currled up and then rolling to right side and vice versa before back to the butt in the air. That gets the gas moving thru.
I'm not sure that w/a pregnancy this would be effective but ... another thing that always helped me was just taking my fingers and "walking" them along my gut following the path of the gas bulges and encouraging them to move on thru down and out. I refer to this and "let your fingers do the walking".
Often my "gas" was the result of bacterial overgrowth and an antibiotic would help. But what is safe to use during pregnancy .......
I'm currently just coming out of symptomatic remission and I have this little gnome "friend" (I call him a guh-no-mee just for the fun of it) that likes to run thru my gut w/a razor blade. Sometimes the little stinker likes to trade his razor blade in for a sword or even a battle axe so as soon as he starts running thru w/his trusty razor blade I jump on him w/a med increase and behaving myself w/what I choose to eat. Even if it means a pureed diet. Ugh!