Totally fine, don't listen to other people. My worst pet peeve is people telling me whats okay and not for the baby. Ive been told I cant eat tabasco sauce, dye my hair or lift small things by only my coworkers and I am more than happy to express my nasty opinions to them on why they should just shut up. Lol
It's perfectly fine even bleaching is you should just do it in a well ventilated room I only know this because I live with a hair stylist lol
Here's some info on beauty treatments during pregnancy from MedHelp.org and the I'm Expecting app. Look for it in Week 13!
http://www.medhelp.org/pregnancy-health/slideshows/Is-It-Safe-Top-Pregnancy-Questions-Answered/2158/6
It's fine really. I've bleached and dyed. This is my fifth
You can colour your hair while pregnant. It's fine.