A female body gets affected by a number of reasons due to different bodily systems. When our pituitary, adrenal, ovary, brain, and thyroid glands don't work effectively then, our body stops balancing hormones and thus we face the problem of irregular periods.
Touch wood, till now I have never faced this issue that almost every girl faces at least once in her lifetime. If you are going through the abnormal days of your life, then you can know the reason behind it just reading this article.