Successful IUI but miscarry natural conception

Hi ladies, has anyone experienced a successful pregnancy with IUI but not when it is a natural conception?

We’ve had a baby through IUI, and have also been pregnant twice naturally but both of those pregnancies have ended in miscarriage. I find it weird that we had such a strong healthy pregnancy with IUI, but obviously some kind of chromosomal issues the other times. Has anyone experienced this?

Im wondering if it has to do with the sperm being “washed” and only good sperm used in the IUI process?