Is it safe to dye your hair while pregnant or breastfeeding?

A friend of mine, who is breastfeeding, recently asked me if it was okay to highlight or dye her hair while breastfeeding. I told her what I knew about the topic - which is that I've known quite a few women who dyed their hair regularly, while pregnant and breastfeeding, and their babies were fine and it didn't seem to dry out their milk or change the flavor making baby go on a nursing strike. I also told her to have the hair salon read the manufacturer's warning on the label since some products might be considered safe while others are advised not to use while pregnant or breastfeeding. I know for a fact that the Brazillian hair straightining "blow out" system tends to lean toward it not being safe for pregnant or nursing women, partially because of the strong chemicals and the amount of time it's in contact with the scalp (the chemicals don't absorb through the hair shaft, only through the scalp - which is why many women chose to highlight over a dying their entire hair) on top of the amount of fumes breathed in during the application of the product as well as the literal puffs of smoke that are emitted during the flat ironing process, but it's also a newer product and hasn't been around long enough to see what, if any, the effects are on pregnant or nursing women.

As it turns out, I actually had my step mom apply this kind of braziliian blow out straightening system within a week, maybe even days, after conceiving my second son.  I was not aware I was pregnant, but we did apply it outside with a breeze (by the pool - can't get that kind of service at a salon!) and just to be extra safe we both wore a mask - I kinda felt like my step mom was a doctor performing a hair operation on me! And in case you're interested, I had a healthy, uncomplicated pregnancy (if you don't include nausea, round ligament pain, and other normal side effects of being pregnant) and an extremely healthy, happy and beautiful baby boy! As for the treatment itself, I have to tell you that it was FABULOUS!!! My entire life I struggled with my hair, and for a short while, it was what I refer to as "normal people hair" it was silky, oh so soft, required so little effort in the mornings, and for the first time I really viewed my hair as beautiful. Then I swam in the ocean, did laps in the pool, and the salt stripped the karotene? out of my silky mermaid hair and slowly but surely the frizzy, puffy locks returned - but I fully intend on having it done again, only I will wait until I'm done breastfeeding.

The main concern with traditional hair dyes, during pregnancy especially, seems to come from breathing in the fumes, which hasn't been proven to cause any harm to baby, rather often times it leaves mom with a major headache, dizzyness or nausea. So ask your OB for his/her opinion and ask your salon what the product's warning label advises. Also, know that from all the research I've read up on, they've done studies on animals (as cruel as that is to take comfort in) and have shown it to be safe.