Hair dyes

Krystal • 24, first pregnancy
My hair is currently ash blonde, and I typically dye my roots about once a month as they grow out. I've seen people say all hair dyes are safe, some say none, I'm conflicted. This is my first pregnancy, I don't know much. 
I've read up on some natural hair dyes such as Naturtint, but some say any dye is safe as long as you're in a well ventilated area. 
Any suggestions/ comments? Should I use the all natural Naturtint, the same color I have been using, or just stop completely?