Dying your hair while pregnant.

Recently I asked my midwife if it was safe for me to dye my hair. She told me there is no harm in it bc my baby does not have lungs to breathe in the chemicals, and the dye is resting on my scalp so there's no way it can even get to the baby. She then told me to make sure the room is well ventilated so I don't accidentally pass out. Then I hear from other people u can't dye your hair. What did your midwife tell u and what do u think ? Safe or unsafe? Wait till your in your second trimester or don't? I want to know what you ladies think.