Me - to i was going to have mine done tomorrow - oh my god - never give that a thought -i am mousey brown and have very blonde colour on my hair - iam going to look like a woman of the night if i cant colour it.
My friend did hers every 3 weeks whilst she was pregnant - and she has a bouncing little boy now.
I'd heard too that you should avoid during pregnancy. I've just started stimming again and my roots are already well over an inch - really want to do a home kit before 2ww even starts, but am now panicking about whether it affects my follies and eggies - ? paranoid? please tell me to stop being so silly and get on with it!!!
I did lots of looking into this sometime back, the details are a little hazy now but I'm sure at least one of the research papers found less (yes, less) incidence of miscarriage and deformities in the 'hair dye' group than in the control group!! In general I think there was very little in it - particularly if you have foils as the dye never reaches the scalp and is therefore not absorbed. But the evidence is always going to be hard to get, just think about it, you have to find hundreds of women who did exactly the same things during the first 12 weeks except that half dyed their hair and half of them didn't. And that's if they can even remember when they did it, how they did it and which dye they used - too many variables to get anything like reliable information!!
But if you feel even slightly concerned then don't do it, it would be terrible to be beating yourself up for it in years to come (even if it wasn't at all to blame). Oh and Henna - usually full of heavy metals so it's just as bad as anything else, sorry.
Hope this helps,