I'm 18w5d today. I felt something strange earlier. I was sitting and putting my feet up to rest then suddenly after awhile, I felt like a light pressure and tightness started to concentrate in the middle of my belly (below my belly button but on top of my pubic bone, if you get what I mean). It lasted only for awhile say 20 seconds or less. :/ Is this normal? Anyone felt this before? It's my first pregnancy by the way. X