Its your choice to do it or not. but one of my good friends did it the entire time and her baby girl if smart as can be. i would personally say it doesn't effect anything. they have people smoking crack while pregnant and they only thing the baby goes through withdraws. people drink every day too and their babies go through more troubles than anything. and drs say its ok to drink a glass of red wine. i wont chance any of it but they have people that risk and do a lot while their pregnant!
I have had multiple friends who have smoked in their pregnancies and their babies are wonderful, smart, and healthy. Asked my doc for one of them who was scared to confess he said he had never seen a study ever in his carrier that has said it harms the fetus. That being said I wouldn't chance it because I'm a scardy cat. Also some states in the US drug test pregnant Mommy's and take action for their findings once the baby is born. By testing the babies meconium i think. That wouldn't be worth it in my personal opinion. Not judging mommys that do of course its up to them what they do. Trust me with morning sickness its tempting lol.
It's very debated against...some say its fine, some say its horrible.
Some have had doctors prescribe it for severe nausea or appetite stimulate.