as long as ur out of your first trimester and your in a well ventilated area you should be fine. I was told that the small amount of chemicals that may get into your blood stream wont affect your baby I am 19 weeks and have dyed mine and my babys perfectly fine
I touched up my roots with color and added highlights in first trimester not even knowing I was preggo. I'm 22 weeks tomorrow and everything is fine.
My hair is black except for my roots lol and my natural hair color is brown
As long as you're in a well ventilated area it's perfectly safe, just don't try a drastic color change since your hormones may make it turn out wrong.