I have three kids n I kept my hair permed during my pregnancies!!! It's not goin to hurt, just don't do it yourself nor dye your hair!!!
you should always talk to you Dr about any concerns during pregnancy but i think hair care hasnt shown much affect on pregnancy as there is much absroption thru the scalp... BUT im not a hair stylist so im not sure, and if you were going to get it done you should get it profesionally done to make sure you hair can handle it as hormones can mess up the way you hair takes the product, this goes for color too... and i think there are some that say once you around 30 weeks?? or past the second semester... im not 100% sure, but def. somethin to know all the facts before trying... hopefully someone with better knowledge responds lol
PS you could even phone around to salons to see what their recommendations are on the matter... good luck!