sex and pregnancy

Ok, this may be a little TMI for people so here's your warning. 
I'm currently 37+6 weeks pregnant and 1cm and a half dialated as of Friday. The dr didn't say anything about pelvic or bed rest but I also don't want to start up labor cuz I'd like to give her another week or two. Has anyone had a similar situation? Did sex start your labor? doctor says she's still high but head down.