Copper
"2 years ago I had it inserted. There was some intense cramping during the "sound" and the actual insertion, but it took less than five minutes, and there was no pain, but slight discomfort, for the rest of the day. I got my period a week early and it was much heavier than before (used to be light 6 days, changed to EXTREMELY heavy 5 days). My period has gotten less extreme over time, and now it is EXTREMELY heavy for 3 days. It took a few months to not feel it at all. Occasionally (once every 6-9 months) sex is too rough and I get stabbing pain in uterus for a few days, but other than that I am able to tell my partner when it is too rough and I don't have any pain. Partner felt it once in the 2  years I've had it. 8/10 for the heavy periods"