Technically, your "monthly" menstrual cycle does not necessarily take place once a month. The average menstrual cycle time for women is 28 days, but your cycle may vary anywhere from 20 to 42 days and still be considered normal.
If you have a short menstrual cycle, it is likely that you will have a period more often than once a month. If your cycle lasts longer, you are one of the luckier ones who may experience less interruption due to periods each month. Of course, if your periods are irregular, that irregularity can cause all sorts of stress and even some fertility concerns if you are trying to become pregnant.
Each month, your reproductive system repeats a regular pattern of events.
