It sounds to me like it could be. A lot of women get constipated in pregnancy. I am like you though, with my first pregnancy, I had NO issues with it at all--actually, I think I was going more than I had been before I got pregnant. But with this pregnancy (16 weeks), I am not going very often at all, and a lot of the time when I do, it's a struggle..
Try orange juice. A couple of glasses a day normally seems to do the job for me. Come to think of it, during my first pregnancy, I was obsessed with oj, I probably drank a litre a day. Maybe that's what kept me so regular?! Good luck!