The length of your menstrual cycle is individual for you. Every person has her own length of their menstrual cycle. You have most probably heard that a menstrual cycle lasts for 28 days. That is the average length for the menstrual cycle of all women. Therefore, many people use that number for a typical menstrual cycle. There are many however who have a menstrual cycle other than 28 days.
The medium length of a menstrual cycle is 28 days but, most commonly, the length of the cycle is somewhere between 24 days and 32 days, when you are experiencing a regular menstrual cycle. If one considers all women, even those with irregular menstruation, it is most common that the length of the menstrual cycle lasts between 21 days and 35 days. It can also happen that you have a menstrual cycle which is shorter than 21 days or longer than 35 days. If you have a cycle that is less than 24 days, it is considered to be a short menstrual cycle.
How you are affected by a short menstrual cycle
If you have a short menstrual cycle, you will have your period more often than many others. You will possibly have your period every third week, while others have their period every fourth or fifth week. A short menstrual cycle also results in more frequent ovulation. Your egg release occurs every menstrual cycle and, if you have a short menstrual cycle, less time pass by between the ovulations. This can be positive if you are trying to have a child. You have many chances to become pregnant, while those with a long menstrual cycle may have to wait for 5-6 weeks between ovulations.
If you have a 28-day menstrual cycle, you will ovulate approximately in the middle of the cycle. The egg release takes place about 12-16 days before the next period.
If you have a short menstrual cycle, the ovulation takes place, nevertheless, about 12-16 days prior to the next period. This means, that if you have a cycle of 21 days, you will ovulate 5-9 days after the first day of your period, i.e. on day 6-10. This implies that you can become pregnant immediately upon the finish of your period, depending on how many days of menstrual bleeding you experience.