I have a Mirena IUD and I hadn't had any kids. My gyno said that it would be more painful to insert than if I had given birth becuase of the cervix never been opened before...and trust me, it was pretty painful to insert. He had to numb my cervix to even begin opening my cervix wide enough to insert it. But it was all worth it in the end...no babies for me for the next few years and no worries about missing pills...plus, i no longer get my period!