What Causes Light Vaginal Spotting Before The Periods?

i am a 25 year old married female who is 5'4 175 lbs and i am writing because i have a medical history of irregular mentrual cycles as i lose weight they are becoming more regular slowly and i am due soon for mine and i spotted once and then for the next 2-3 days after that i faintly spotted atleast once a day . is this normal or not .