bleaching hair while pregnant

So my cousins doctor told her it was completely okay to bleach her hair while pregnant, just to be in an open room so you don't inhale the chemicals, because the chemicals don't go deep enough to harm your baby. But she said it was 100% safe as long as she had her windows open and fans blowing and in a big open room. Have any of you bleached/colored your hair while pregnant? (DONT COMMENT TO START A DEBATE THIS IS ASKING OTHER WOMAN ABOUT EXPERIENCE)