Hair dye options?

I dye my hair very often last time but now that I’m 8 weeks pregnant, I try to avoid hair dyes all this while but my black hair roots are really getting very hideous now. I just need a hair colouring once, to make everything black. Any of you dyed your hair when you were pregnant? How many weeks were you in when you did it? Which salons did you all go to and is there a specific hair dye type that we should be looking for? Thanks!