Sex is fine anyway unless Dr says no sex. Once you get that far along doggie style is about the only way to do it..lol...
Sex will not trigger labor until the body is ready for it. Unless your doctor has advised against sex the you are fine. However bc organs move to accomodate your now ever growing baby and they are swelling a lot more now too, its best to find a comfortable position.
I dont think it will put u in early labor