It is still safe to have sex in the 3rd trimester?

It is if you have been having a healthy and normal pregnancy. However, it can be quite difficult to do so as your third trimester progresses, you'll get bigger and it might not be too comfortable. But it is possible as long as you can think of creative ways ( e.g. positioning during sex) to avoid discomfort. You might get more tired than usual in the third trimester, so be sure to take it slow. http://www.thebump.com/a/best-sex-positions-for-third-trimester