Quick question about having sex

Okay so at 26-27 weeks I started having contractions, they were little & I was closed, no dilating & everything was what is should be. They don't know why the contractions started but they sent me home to rest and it has stopped. They told me I was on pelvic rest and to take it easy, that also ment no sex. No orgasms of any kind..... They said at least until I talk to the doctor later that week but when we went I forgot to ask when it would be okay again. Well I'm 29 weeks now & I haven't really had any symptoms of preterm labor but I was wondering why they said no sex or orgasms? What would one do? Would it hurt the baby or maybe put me into labor? Anyone have any thoughts? & anyone have an idea on when it would be okay again? (I'm asking the doctor in a week) but just confused on why no orgasms?