My period flow has drastically reduced over the past few months. Though it's regular it hardly lasts 2 days. 1st day is fine, towards the end of 2nd day almost over and very slight spotting (negligible) on 3rd. I have also gained 5-6kgs suddenly during this time. And am unable to lose this weight even though I lead an active lifestyle with regular exercise and swimming. Are these two interlinked? Or symptoms of something specific that I should get checked for? I have used birth control pills. Can these be the side effects?