Can i use a derma roller at home while pregnant? i clean it well in between. i want to use it on my stomach and face. im five months pregnant?

What do you expect to gain from it? If you think it will prevent striae , you are likely to be disappointed. You are unnecessarily risking skin infection from the skin punctures. For the sake of your and your baby's health, you should be under the care of an obstetrician and she/he can advise you better. Wish you good health and a healthy baby!