I didn't do it during pregnancy because I was too nervous about the chemicals, but honestly a lot of mums I know did and their babies were fine. The main thing is making sure the salon is well-ventilated and your gynae is okay with it, so definitely ask during your next appointment just to be safe. Some mums found that their hair texture changed a bit during pregnancy anyway, so it might not hold as well, but if you really need it done the timing and safety chat with your doctor matters most.
I didn’t do hair rebonding but I did dye my hair during trimester 2. If you’re unsure, best to check with your gynae.