IUDs do not cause bleeding after sex. If you get bleeding after sex, you need to see a doctor, and that may not be but a must. I was referring to actual bleeding, rather than spotting, though it's wise to check out spotting just in case. Both copper and Mirena
IUDs may cause irregular bleeding, for the first few months in particular, but that's not the same as distinctive bleeding after sex.If your feel that
bleeding is significant/repetitive I suggest you to meet your doctor to avoid further blood loss.Hope this helps.Take care.