Hair dye and pregnancy questions / non toxic hair dye?

So I know that there are probably plenty of women who dye their hair during pregnancy but does anyone really know about the safety of it or have you gotten advice from your doctor on it? Also what does anyone know about nontoxic hair dye? There is a salon near me that does what they consider to be more natural and nontoxic products and they say they have nontoxic hair dye but I don’t know what that means or if the product is not as effective and gives a good quality result on the hair or if it works just the same. ??