I did once and my hair didn't dye right so I wouldn't again. You have to do what you feel is right.
Professional hair is different than store bought hair color. The kind you can buy in the store has high amounts of ammonia and metallic dyes which are the things you should steer clear of. Demi (professional) hair color is the way to go. Personally, I do highlights/lo - lights with a quick toner at the end after the first trimester.
I'm a color specialist and it is Ok to color your hair. . You Can use ammonia free if you are scared about the ammonia but you can use normal color as well. Be In well ventilated area or you can wear a mask to cover your nose and mouth so you don't smell the fumes. . Especially If you get highlights. I have heard your hair might go funny colors due to hormones but all of the colors I have done on pregnant ladies turned out awesome. . So I guess it just effects people differently. I feel way better about myself when I have my roots done so If you are like me. .Then I say you should. It's always nice to pamper yourself. :)
I've colored my hair about 4 times throughout my pregnancy im now 36 weeks and baby is perfect and so am I can't stand to be looking incomplete lol.. Got to enjoy the glow the pregnancy gives us :-)
I'm aged 25 and suffer with greys haha but I use ammonia free hair dye a couple pound dearer but worth it as it dnt smell etc and I'm 30 weeks pregnant now and everything's been good so far in my pregnancy the hair dye hasn't effected it xx