Braxton Hicks Contractions

I've been getting quite a bit of Braxton Hicks contractions and tightenings on my tummy lately. I am 31 weeks preggers today. I hope this is not a sign of preterm labor. I've also experienced these contractions and tightenings for both my previous pregnancies but thank God, I did not go into preterm labor. When I was carrying Alycia though, I had to be on partial bed-rest when my cervix started to shorten at week 20+ of my pregnancy.