I really feel you on this, being a first-time mum and wanting to try everything that might help is so natural. I honestly would not try it without checking first, especially since you are only 31 weeks and there is still quite a bit of pregnancy left to go. It might be good to bring this up with your gynae or PD at your next visit, just to get the green light before trying anything new. Better to be safe and get a proper answer from someone who knows your full history, right?