It is important to understand why you have periods, and what is actually happening with your body in order to explain the answer to your question. The female body, in general, goes through the cycle of preparing to become pregnant roughly once a month. In doing this, an egg is released from the finite stores that each woman is born with. This release is directed by hormones that are, for the most part, orchestrated in very specialized parts of your brain (which take feedback from the rest of your body). In order to harbor the (possibly) fertilized egg, your uterus is also prepared every month to receive the egg. Normally, your uterus is a muscle with only a thin layer on the inside, which does not have enough blood supply or nutrients to protect and help an egg grow. The hormones that are involved in the rest of the cycle also cause the lining of the uterus to grow and prepare. When the egg passes without becoming pregnant, the hormones change and the lining has to slough off. When this happens, it happens abruptly. This is followed by a slower sloughing that can occur over a few subsequent days. Please speak with your doctor
about your questions or concerns, especially if you are experiencing heavy menstruation.