Spotting with coil although never had a period with it

Dear Ask The Doctor: I have the merena coil fitted and have never had a period with it or any other form of contraception but no for 1 yearw have a sudden onset of spotting what could it be?

Dear Siobhan: It is common to experience irregular bleeding and spotting between menstrual periods periods, especially during the first 3 to 6 months after Mirena. After your body adjusts, periods usually get lighter and the number of bleeding days is likely to decrease, but may remain irregular. You may need to consult your health-care provider if the bleeding remains heavier than usual or if the bleeding becomes heavy after it has been light for a while.