im a hairdresser and even though i know that its probably ok to colour my hair, im just going to change over to foils during my pregnancy. this way the chemicals arent touching my scalp. im probably being over cautious because i am in contact with a lot more of these kinds of chemicals than most people.
i would definately colour my pregnant clients hair without questioning their choice but i always mention that some people dont feel comfortable doing it and occasionally the colour does not react the same way as it normally would due to the change in hair texture and condition. (some people may be oilier or drier or their hair may thicken which can give the illusion of darker results)
in the days of perming, we always warned our pregnant clients that their wave may not be even as hormonal changes cant be predicted.
having said all that, and even though im not putting colour on my own skin, i would agree that its ok to do it but just not for me personally. (you know, because im sooo exposed to it already) just try and fan away the fumes with a magazine or something as i read that they are not ok to breathe in. (again this might be ok if its only done once every 30days when your colour might need refreshing)
strangely, even though im so cautious with hair colouring, im still using skin products that are a bit illegal in the world of pregnancy. 8-[

beck