Bactrim

Okay so I got prescribed the generic brand for Bactrim due to a skin infection (got bit by a spider). The dr knows I'm 10 weeks pregnant and as I was going to take the pill I read that it can cause harm to the fetus. The list of harmful things is horrific. Anyone take Bactrim? I think that's what they prescribe when ur pregnant with a UTI. I'm just scared to take it and am waiting for the on call nurse to call me back. It's not worth taking the chance to harm my baby but at the same time I don't want my arm to fall off from being infected.