What causes short menstrual cycles?

Short menstural cycle occurs due to many reasons.This may be due to hormonal imbalance and one of the reason can be poly cystic ovary syndrome(PCOS),This occurs due to increased exercise as well.But the situation is same even after 5-6 months there may be some serious problem,in that case you should immediately visit to your gynecologist.

There can be various reasons for short menstrual cycles: one of them is
- Hormonal imbalance: Women with hormonal imbalances may require estrogen shots or medication to get their cycle back on track. Women who experience a condition known as polycystic ovarian syndrome (PCOS) may be put on medications such as glucophage to regulate their periods. Other women could be prescribed birth control pills to help regulate the frequency and length of their menstruation.
However, there are women for whom this not a cause of concern, but if it continues for several months then probably they should visit their physician.