A menstrual cycle begins when you get your period or menstruate. This is when you shed the lining of your uterus. This cycle is part of your reproductive system and prepares your body for a possible pregnancy. A typical cycle lasts between 24 and 38 days.
Menstruation is the monthly shedding of the lining of your uterus. Menstruation is also known by the terms menses, menstrual period, menstrual cycle or period. Menstrual blood — which is partly blood and partly tissue from the inside of your uterus — flows from your uterus through your cervix and out of your body through your vagina.
Menstruation is driven by hormones. Hormones are chemical messengers in your body. Your pituitary gland (in your brain) and your ovaries (part of your reproductive system) make and release certain hormones at certain times during your menstrual cycle.
These hormones cause the lining of your uterus to thicken. This happens so that if a pregnancy would occur, an egg can implant into your uterine lining. Hormones also cause your ovaries to release an egg (ovulation). The egg moves down your fallopian tubes, where it waits for sperm. If a sperm doesn’t fertilize that egg, pregnancy doesn’t occur. The lining of your uterus breaks down and sheds. This is your period.
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The menstrual cycle is a term to describe the sequence of events that occur in your body as it prepares for the possibility of pregnancy each month. Your menstrual cycle is the time from the first day of your menstrual period until the first day of your next menstrual period. Every person’s cycle is slightly different, but the process is the same.
The average length of a menstrual cycle is 28 days. However, a cycle can range in length from 21 days to about 35 days and still be normal.
The days between periods is your menstrual cycle length. The average menstrual cycle lasts 28 days. However, cycles lasting as little as 21 days or as long as 35 days can be normal.
Most people have their period (bleed) for between three and seven days.
A period is normal if it’s anywhere between three and seven days. While on the shorter end of the range, some people have a menstrual period for three days. This is OK.
The rise and fall of your hormones trigger the steps in your menstrual cycle. Your hormones cause the organs of your reproductive tract to respond in certain ways. The specific events that occur during your menstrual cycle are:
People start menstruating at the average age of 12. However, you can begin menstruating as early as 8 years old or as late as 16 years old. Generally, most people menstruate within a few years of growing breasts and pubic hair.
People stop menstruating at menopause, which occurs at about the age of 51. At menopause, you stop producing eggs (stop ovulating). You’ve reached menopause when you haven’t gotten a period in one year.
Some people experience symptoms of menstruation and others don’t. The intensity of these symptoms can also vary. The most common symptom is cramps. The cramping you feel in your pelvic area is your uterus contracting to release its lining.
Other signs you’re getting your period are:
Your menstrual cycle can change from your teen years to your 40s or 50s. When you first get your period, it’s normal to have longer cycles or a heavier period flow. It can take up to three years for young people to have regular cycles after they begin menstruating. A normal menstrual cycle is a cycle that:
Once you reach your 20s, your cycles become more consistent and regular. Once your body begins transitioning to menopause, your periods will change again and become more irregular.
It’s also normal for your period to change during other life events that affect your hormones, such as after childbirth or when you’re lactating.
Irregular menstruation describes anything that’s not a normal menstrual period. Some examples of an irregular period are:
You can expect to lose between two and three tablespoons (tbsp.) of blood during your period. Some signs of irregular period bleeding are:
It’s normal to experience some variation in the amount of bleeding each cycle. It’s also important to remember your normal may be different than someone else’s. Try not to compare. Talk to a healthcare provider if you’re concerned about irregular or severe bleeding during your period.
It’s a good idea to be aware of your menstrual period. Not getting a period may not seem like a big deal, but an irregular period can be a sign of a problem. Your healthcare provider will ask you about your most recent period and menstrual cycles. Knowing what’s normal for you can be very helpful to your provider.
Tracking your period can also be helpful in knowing when you ovulate, which is when you’re most likely to get pregnant. It can also help you plan ahead or prepare for period bleeding during a special event or vacation.
To track your period:
There are also apps that do all of this for you that you can download on your phone or tablet.
Contact your healthcare provider if:
A note from Cleveland Clinic
Your menstrual cycle provides valuable insight to your healthcare provider about your reproductive health. A normal menstrual cycle can last between 21 and 35 days. You can expect to bleed between three and seven days each time you get your period. Contact your healthcare provider if you have questions or concerns about your menstrual cycle. In some cases, an irregular cycle could mean you have a health condition that needs treatment.
Last reviewed by a Cleveland Clinic medical professional on 12/09/2022.
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