I'm also a cosmetologist. My first son is .... Perfect ;) like everyone about said the key is ventilation and minimal skin contact. If you're really worried about it stick to foils :)
I bleached my naturally dark hair throughout my entire first pregnancy and my son is just fine. Try to control the amount of skin/scalp contact with whatever you choose be it bleach or dye and make sure you are in a well ventilated area. Don't worry about it.
Im a hairstylist .... you can bleach your hair. there have been no studies that have found it harmful however avoid having it touch your scalp and stay in.a well ventilated area!
Its ok to dye your hair with regular hair dye but not to sure about bleaching. You should ask your doctor.
not sure about bleaching, I've read dyeing is probably ok, but the smell could be an issue.