Branxton Hicks ?????

Hello,

Just wanted to ask anyone who has had experience with lots of branxton hicks... this is baby number 4, I am 18+3 and for the past 4 nights when im in bed my stomach starts getting really tight and stays tight for approx 10-15 seconds and then starts to fade slowly.. It happens a few times in a row. I have only noticed this at night time when I'm in bed, seems to be exactly the same time aswell...

I'm just wondering if this is normal as I'm only 18 weeks, with my previous pregnancies I wasn't feeling anything until I was in my third trimester..