I never had an ovarian cyst before Mirena. One of Mirena's adverse effects is precisely ovarian follicle enlargement. Now I have one and also crazy ovaries overworking!!!!
Please see folder Mirena Clinical in here, just click at the upper bar PDF and look for the product monograph published by the Canadians in their Mirena web site. Read the adverse effects and everything related to the ovaries very carefully and draw your own conclusions. If necessary take it to your Doctor, they insist Mirena is wonderful $$$$$. The statistics are from 2000 so they have to be inaccurate by now!!!! We are too many complaining about the evil thing.
Best of luck! By the way you may also immediately gain weight with Mirena.