Sex in 3rd trimester

This is my second baby and im currently 33w pregnant. My SO recently mentioned that i wasn't as tight down there anymore and it was harder for him to finish because of how loose it felt. Same thing happened with my first baby but then it went back to normal after she was born. I dont remember how close to labor, my SO started complaining of it not feeling as tight which is why im wondering if any of you ladies have also experienced this? Im not too worried because like i mentioned, it was even tighter than normal after baby was born im just very curious to know if and at what point did you start experiencing a lack of tightness during sex, how soon did labor follow and what did you do in the mean time to make sex more pleasureable for both? (I have a history of preterm birth so i wouldnt be too surprised if labor is right around the corner)