Did Bella marry Edward before getting pregnant?

Yes, they were married before she got pregnant. (The answer below is incorrect about not having sex until Bella was a vamp.) Edward & Bella had sex for the first time on their honeymoon but Bella was still human. That was Bella's condition for agreeing to get married - she wanted to experience sex as a human, but Edward wouldn't have sex with her until they were married. Bella and Edward couldn't have sex until after she became a vampire because he could hurt her. They were married before her transformation, so, although not mentioned in the book, they must have been married when she got pregnant.