How long is too long to go without a period?

Patient: I haven’t had a period for about 10 years from being pregnant to nursing then an i.u.d. with each of my 3 kids. Is there any research on the effects of no period for such a long time? I can’t complain it is definately great to not deal with but I wonder is there any long term side effects?,and should I have my I.U.D. removed for a period of time to let my body do what its supposed to do?