Ive had mirena iud for 3 years now. my cycles have started bk to being 10-12 days long. why? also before the mirena my cycles were much shorter. cycles are still light though just too long. 33 years old?

There may be other causes for extended menstrual bleeding not related to an IUD, however, uterine contractions can force the IUD into the cervical canal, which will cause pain and additional bleeding. See your GYN physician who may order ultrasound to determine whether the IUD is not in proper position, which may need replacement with a new IUD.