Many pregnant women have concerns about the safety of hair dyes and permanents during pregnancy.
There is no scientific data on this question one way or the other, but it seems unlikely that these types of exposures are harmful. Keep in mind that in contemporary society, we are all exposed to many chemicals each day. Remember that every pregnant woman has at least a 1 in 100 chance of having a baby with a major birth defect. Avoiding as many chemicals as possible would seem prudent, but you can not avoid everything. Many childbirth classes advocate a set of exercises known as perineal massage to prepare the birth canal for delivery.