Hair dye and pregnancy??

My hair is poop! I would like to dye it or fix it from this ugly brown color back to an auburn, but I am afraid! 
I heard in your third trimester it's basically fine. I think I even dyed my sisters hair for her when she was 7 or 8 months pregnant..
I'd like to look or feel good for maternity pics and our baby shower.. Any advice or recommendations on possibly some super natural, or not so harsh hair dyes? (Not henna)