30 weeks pregnant if i apply nail paints and use thinner will the smell harm my baby if i inhale? i heard pregnant women should not use nail paints.

Product safety issue: Generally speaking, the less product into or on your body during pregnancy the better off for your fetus. That being said if you want to have your nails painted i would recommend making it a rare and special event, not weekly, and choose a salon that will be sensitive to your pregnancy by making sure you are not breathing in fumes and using safer products (toluene free products, for example).