Hi there
It's not neccessarily a worry. It can be a sign that you have a little bit of piles trouble. (This is usually caused as you get bigger because pressure if being put on your back end by the extra weight!) It can happen earlier, especially if you are not sitting down more and less active in your daily routines.
Pregnancy does strange things - I found when I got pregnant, that I simply couldn't poo unless I was reading something. Anything - even the label on an M&S towel in the bathroom was fine, but I had to be reading!
Do mention it at your next check up but it doesn't sound like anything to worry about.
