As long as it's not in your first trimester I personally waited til my Ob gave me the ok :)
My doc says that as long as chemicals don't touch your scalp. But in his opinion it was better to wait. But he also mentioned that dying your hair hasn't been related to any problems with newborns.
They actually say the second trimester is the safest time to do it :)
I'm getting highlights at a salon tommorrow but I'm in my second trimester. I wonder if it's ok. :/ Everyone around me including my grandmothers who's been a nurse for 30 years said it's totally fine.
You can dye your hair. Make sure it's ammonia free and your in a well ventilated area.