A: As you know, there are several categories of hair dyes. There are temporary dyes that coat the outside of the hair, semi-permanent dyes that wash out after multiple washings, and permanent or oxidative dyes. Different dyes contain different chemicals, and manufacturers change their formulations, making it difficult to study the effects of dyes. We have limited research on hair dye in pregnancy. There is evidence that oxidative hair dyes are carcinogenic in laboratory animals, but there's no evidence of increased cancer in humans. We do know that low levels of hair dye can be absorbed into the scalp, and hair dye is excreted into the urine. However, the quantities absorbed are minimal, and it's unlikely that hair dye causes problems in pregnancy.

While many women continue to color their hair during pregnancy, there are no reports of adverse outcomes. If you choose to dye your hair and want to be the most cautious, wait until your second trimester to do so, use gloves to protect your skin when dying your own hair and avoid permanent dyes.

Pregnancy tends to affect hair growth and quality, and may cause hair to react different to hair dye. Hair may become drier, oilier, straighter or curlier. Hair naturally becomes more full and shiny as pregnancy progresses, and you may find that you enjoy the appearance of your hair without any additives.