Is it safe to use the no no hair removal on my face whilst pregnant?

Yes and no: I don't think there is any problem with doing this while you are pregnant but I think these products are very harsh on the face and don't recommend them at all.

NO NO: I think it is a good idea to check with your doctor for any question regarding your pregnancy. There is very little research on the subject but talk to your doctor

Probably but: There is no data for it's use during pregnancy. It is a form of mild thermal hair removal. You should review it's use with your OB/GYN, as if you are prone to stress and the associated physiologic strain of such, then you may want to avoid something like this.