A.M.
Hi S.-
As a hair-stylist i have several clients that have asked me this question over the years. This is what i respond with...
Of course its ultamitly YOUR decision but here is a little insight of the chemistry of hair color.
The color molecule is LARGER than your pores. It CANNOT penetrate your skin. It can stain your skin but not penetrate it. Of course there is being around chemicals. Hundreds if not more hair-stylist get pregnant and work EVERYDAY with the chemicals, touching them, breathing them etc... and their children have been fine. I have two kids of my own and worked through my pregnancies. My kids were born full term, healthy and happy!
Its your decision but if i can say anything... i would NOT worry about it. And with using aveda demi-color (i work at a aveda salon) their color line is so "soft" compared to other color lines. You are there ...what...every 4-6 weeks. You will be fine and so will baby. But if you feel uncomfortable talk to your stylist, she can maybe keep it off your scalp and or wait till your out of your first trimester.
Good luck and if you have any questions just email me.
A.