Levonorgestrel
"I must be one of the lucky ones.   I'm 30 just had my 2nd child 4 months ago which is why I'm sure it was easy.   Literally had one cramp during insertion.   Had it put in yesterday and I'm experiencing NO cramping whatsoever.   Am lightly bleeding though so we shall see how long this lasts.   Not giving 10 stars bc I'm on only on day 2 so I don't have much experience with it."