Is it safe to color my hair during pregnancy?

Yes: In the first half of the last century, hair coloring actually contained "coal-tar dyes" which were not only unsafe for the pregnancy, but were questionable for the mom as well! today's hair colorings are safe -- therefore, safe for pregnant moms.

Yes: Sure. Best done in well ventilated facility (the fumes can be unpleasant). Note that hair may grow faster, thicker, with increased density due to hormones. Unfortunately this will reverse itself, sometimes rapidly within a few months after delivery.

After trimester #1: There are some hair dyes that are safe to use in pregnancy, but it is best to wait until after your first trimester is complete. This is when the baby is developing the most, and it is crucial nothing interferes with the process.