It's 50/50 in that you either will or you won't.

I've tried loads of different makes and never once had any reaction, but it's wise to have it done - imagine the unpleasantness of your scalp being covered in a potentially painful, at the very least itchy, rash.

Hope all's well and that you can get the colour you're after.

The pregnancy will make a difference to the way your skin reacts. It is essential to have a skin test.
I tried to get a perm when I was pregnant and my hairdresser nearly threw a fit - did a strand test snd showed m what looked like withered rubber bands.
Don´t be disappointed if you can´t have your hair coloured - all will return to normal after the birth.
Good luck.