I've found that bh's feel like a tightening of the uterus, goes hard as a rock and makes me feel a bit breathless, and I usually get more when I'm more active, although at this stage of the pregnancy I feel like I'm getting them all the time! It's actually a good thing as your body is getting itself ready for labour. It's amazing that our bodies know what to do without us doing anything! I was also told that when you get a bh it can help to breath through them, or practice any other techniques you might use in labour, in other words use them as practice runs for labour contractions. Good Luck!!