abnormal uterine bleeding
"I had Mirena placed in January 2012 to help with very heavy periods and low iron. Relatively comfortable placement, by a GP who specializes in women's wellness. Felt strong cramps for about 15 seconds during placement, other than that it felt like getting a pap. First month constant spotting and bleeding. Headaches. Cramps. (Very unusual for me but also very manageable). First period 30 days after placement 75% reduction in bleeding and days of period as compared to my normal periods.
The headaches and cramping form the first month slowly dissipated, and now I don't get either anymore. 
I have not had a period since February, took a pregnancy test just to be safe, it was negative. I didn't expect much from Mirena...what a great surprise!"