I'm 17 weeks with my 3rd and had sex the whole time with all my pregnancies. The only time it did anything was with my last one I was already have contractions and sex helped them become more consistent but I was ready for baby. If your really worried have your s.o wear a condom its the seman that helps with labor not the actual sex.
As said above your should be fine. Sex isn't likely to induce labor unless your body is already ready for labor so as long as your Dr hasn't told you not to have fun!
U should be fine. Sex does help enduced labour but only if ur abt to already go into labour on ur own. Ur 38 although still close to 40 weeks u should still be fine unless ur already getting symptoms of labour like water breaking or the contractions