Aih, at 39 weeks you're so close already! That tight, stretching feeling down there is pretty common at the end, a few of us felt exactly the same thing before labour started, macam ada urat yang tegang-tegang. With your second baby it could be a sign your body is preparing, tapi honestly better to give your doctor or midwife a quick call or message just to confirm everything is okay down there, especially if it's painful or different from before. Praying you go into labour soon, jiwa raya tu is right around the corner!