what causes or what makes the uterine polyps?

Hi! I had uterine polyps removed during hysteroscopy because they were causing me troubles. I was suffering from bleeding between my periods, and had severe cramping during periods, so my gynecologist decided to remove them and I agreed because I certainly didn’t want them inside. I heard that sometimes they can cause problems with fertility, so I definitely wanted them out as I haven’t had any children yet.

What about you? Have you seen them on sonohysterogram? How big are they? Are you experiencing any troubles? I haven’t had any problems since I got them out. However, I heard that they can reappear.
I think it is actually not known what causes polyps but I know that a person can develop them in a colon and stomach as well. Because it is not known what causes them, we can’t prevent them. Luckily, they are not cancerous.