Cycling while pregnant

I’m currently nearly 12w and I bike commute to work 4 1/2 miles each way. I’ve been riding this route on this bike for *years*. Today my uterus was very much opposed to the ride. I experienced discomfort every time my butt was in the saddle. Even just lifting millimeters off the seat was enough to ease it. I don’t think it was my riding position, though at some point I’m sure I’ll have to switch from a road set up to a cruiser (I’m seriously not looking forward to that).

Have any of you had similar issues? Or other pains while biking while pregnant?