I noticed a celebrity phenomenon recently when watching a special about the baby boom happening in the entertainment industry. It seems celebrities are not only producing babies at a somewhat alarming rate, but they are also changing their outward appearances to go along with these changes.

Obviously, the most notable changes are the prevalent baby bellies, but watching the procession of these baby bellies go by, you will notice another change common among the mother’s sporting them: a change in hair color. Many famous women, who have never been seen as anything but blonde, red headed or even rich brunette, are suddenly and quite literally showing their true colors. This return to their roots (for the lack of a better word), got me thinking about the various pregnancy changes women undergo. They don’t have control over how their belly is growing or if they are going to be one of those women who sprout whiskers, and now it seems they don’t have control over the color of their hair. What is so wrong about a pregnant woman dying her hair? Is this just more of pregnant women wanting to be true to themselves and embrace a “new” persona along with motherhood, or are there really dangers associated with hair coloring?

Most commercial hair dyes contain a host of chemicals, additives, stabilizers and preservatives. Though these products are only applied topically, it is important to remember the skin is porous and acts as transport both in an out of the body. Just as your scalp sweats and excretes oil, so does it absorb materials applied to it. When a pregnant woman gets her hair dyed, some of the chemicals in that dye are introduced into the bloodstream through the skin. The medical community has voiced many concerns about this transmission, including the potential for developmental problems and birth defects in babies whose mothers frequently color their hair during pregnancy. The risks are particularly high for those who use hair dye during the first trimester. 

Further studies, however, have linked maternal hair dye use to much more serious potential consequences. In a study of over 500 cases of childhood neuroblastoma (a cancer), researchers identified a link between maternal hair dye use in the month prior to conception and/or during the actual pregnancy, to the moderately increased risk of the baby developing neuroblastoma. Temporary dye showed a stronger association with the cancer than permanent hair dye. Though further research will need to be undertaken to completely understand these risks, mothers are urged not to use any form of chemical hair dye immediately before or during pregnancy.

Source: McCall EE, Olshan AF, Daniels JL. Maternal hair dye use and risk of neuroblastoma in offspring. Cancer Causes Control. 2005 Aug;16(6):743-8.