i have been having light periods for the last four months but they are regular what might be the problem

Hello Anon

Thank you for writing.

There may be no problem at all. As long as your periods are regular, this sounds like normal periods, albeit periods that have changed for you over the past few months. A simple change in body chemistry can cause this; it's not a generally a cause of concern. Periods change over the years as a woman's body changes. Talk to your gynecologist if you have further questions.
Best,
Susan