The heaviness of menstruation is usually determined by how much endometrial lining has built up over the course of the month. For some women, light menstruation is normal. But for others, bleeding lightly or for only two days or less may be cause for concern.
Hypomenorrhea can be caused by:
Pregnancy
Sudden changes in weight
Stress
Hormonal contraception
Your treatment plan will vary depending on the underlying cause of your condition. Call your primary care physician, gynecologist or OB/GYN if you are concerned about light periods.