The limited evidence that's available suggests that it's probably safe to dye your hair during pregnancy. The Organization of Teratology Information Services (OTIS), which provides information on potential reproductive risks, says that animal studies are reassuring and that there are no reports of hair dye causing changes in human pregnancies, despite the fact that many women have colored their hair during pregnancy. OTIS also points out that very little of the chemicals in hair dye is actually absorbed into your system.

That said, if you're still concerned, consider waiting to color your hair until the second trimester, when your developing baby is less vulnerable. Also, instead of using an all-over hair color, consider a process like streaking, highlighting, painting, or frosting, in which the chemicals have little or no contact with your scalp. (Any hair-coloring agents absorbed into your system would come through your skin, not through your hair shaft.)
Pure henna (Lawsonia inermis) – a semipermanent vegetable dye that's been used for thousands of years – is considered safe.
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