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Your Period

Menstruation (a period) is a major stage of puberty in girls; it is one of the many physical signs that a girl is turning into a woman. Some girls cannot wait to start their periods, and others may feel afraid or anxious. Many girls do not have a complete understanding of a woman's reproductive system or what actually happens during the menstrual cycle, making the process seem even scarier.

Puberty and Periods

When girls begin to go through puberty (usually starting between the ages of 8 and 13), their bodies and minds change in many ways. The hormones in their bodies stimulate new physical development, such as growth and breast development. About 2 to 2 1-2 years after a girl's breasts begin to develop; she usually gets her first menstrual period.

The start of periods is known as menarche. Menarche does not happen until all the parts of a girl's reproductive system have matured and are working together.

As a girl matures and enters puberty, the pituitary gland releases hormones that stimulate the ovaries to produce other hormones called estrogen and progesterone. These hormones have many effects on a girl's body, including physical changes, growth, and emotions.

About once a month, a tiny egg leaves one of the ovaries—a process called ovulation—and travels down one of the fallopian tubes toward the uterus. In the days before ovulation, the hormone estrogen stimulates the uterus to build up its lining with extra blood and tissue, making the walls of the uterus thick and cushioned. This happens to prepare the uterus for pregnancy: If the egg is fertilized by a sperm cell, it travels to the uterus and attaches to the cushiony wall, where it slowly develops into a baby.

If the egg isn't fertilized, though—which is the case during most of a woman's monthly cycles—it does not attach to the wall of the uterus. When this happens, the uterus sheds the extra tissue lining. The blood, tissue, and unfertilized egg leave the uterus, passing through the vagina on the way out of the body. This is what we know as a menstrual period. This cycle happens almost every month for several more decades (except, of course, when a female is pregnant) until a woman reaches menopause and no longer releases eggs from her ovaries.

Why Haven't I Started My Period Yet?

Everybody goes through puberty at different speeds. Some girls begin their period as early as age 8 or 9; others do not get going until they are 15 or 16. It all depends on your hormones. When you start puberty is partly linked to genetics.

How Often Does a Girl Get Her Period?

Just as some girls begin puberty earlier or later than others, the same applies to periods. Some girls may start their period as early as age 10, but others may not start until they are 15 years old.

The amount of time between a girl's periods is called her menstrual cycle (the cycle is counted from the start of one period to the start of the next). Some girls will find that their menstrual cycle lasts 28 days, whereas others might have a 24-day cycle, a 30-day cycle, or even longer. Following menarche, menstrual cycles last 21-45 days. After a couple of years, cycles shorten to an adult length of 21-34 days.

Irregular periods are common in girls who have just started. It may take the body a while to sort out all the changes going on, so a girl may have a 28-day cycle for 2 months, then miss a month, for example. Usually, after a year or two, her cycle will become more regular.

As a girl gets older she will probably find that she can predict when her period will come. In the meantime, it is a good idea to keep track of your menstrual cycle with a calendar.

How Long and How Much?

The length of a girl's period can also vary. Some girls have periods that last just 2 or 3 days and others may have periods that last 7 days or longer. The menstrual flow—meaning how much blood comes out of the vagina—can vary widely from girl to girl, too.

Some girls may be concerned that they are losing too much blood. Though it may look like a lot, the average amount of blood is only about 2 tablespoons for an entire period. Most teens will change pads 3 to 6 times a day.

Especially when menstrual periods are new, you may be worried about your blood flow or whether your period is normal in other ways. Talk to a doctor or nurse if:

It can take up to 3 years from the time a girls period starts for her body to develop a regular cycle. Even then, what is regular varies from person to person. Your cycle can range from 21 to 45 days.

Changing hormone levels might make your period short one month (such as 2 or 3 days) and longer (such as 7 days) the next. You might skip a few months, get two periods almost right after each other, have a really heavy period, or one so light you almost do not notice it. (If you are sexually active and you skip a period you should call your provider ASAP).

All this irregularity can make planning for your period a real hassle. Try to keep track of when your last period started, and guess that about 4 weeks from that day you could be due for another. If you are worried about wearing that cute dress and suddenly starting your period at school, just make sure you pack protection. Carry a pad or tampon in your backpack, and wear a pantiliner to handle when it initially starts.

When it comes to periods, every girl's body has a unique (and unpredictable) timeline for getting on track. If your period still has not settled into a relatively predictable pattern after 3 years, or if you have four or five regular periods and then skip your periods for a couple of months, make an appointment with your provider to check for possible problems.

Cramps, PMS, and Pimples

Some girls may notice physical or emotional changes around the time of their periods. Menstrual cramps are pretty common—in fact, more than half of all women say they have cramps during the first few days of their periods. Doctors think that cramps are caused by prostaglandins, a chemical that causes the muscles of the uterus to cramp.

Depending on the person, menstrual cramps can be dull and achy or sharp and intense, and they can sometimes be felt in the back as well as the stomach. These cramps often become less uncomfortable and sometimes even disappear completely as a girl gets older.

Many girls and women find that over-the-counter pain medications (like Tylenol or Motrin) can relieve cramps. Also, taking a warm bath or applying a warm heating pad to the lower abdomen may decrease the discomfort. Exercising regularly throughout the monthly cycle may help lessen cramps, too. If these measures do not help, ask your doctor for advice.

Some girls and women find that their period brings about many emotional changes such as: sadness, being easily irritated, and anger. These types of emotional changes may be the result of premenstrual syndrome (PMS).

PMS is related to changes in the body's hormones. As hormone levels rise and fall during a woman's menstrual cycle, they can affect the way she feels, both emotionally and physically. Some girls, in addition to feeling more intense emotions than they usually do, notice physical changes along with their periods—some feel bloated or puffy because of water retention, others notice swollen and sore breasts, and some get headaches.

It is also not uncommon for girls to have an acne flare-up during certain times of their cycle; again, this is due to hormones. Fortunately, the pimples associated with periods tend to become less of a problem as girls get older.

Menstrual Problems

Although most of the strange stuff that goes along with a girl's period is completely normal, there are a few conditions that can be more serious. If you suspect you have any of these problems listed below; see your provider for advice.

What to Do if You Suspect a Problem

When you have questions about your period or anything else related to your development, talk to your provider. This is particularly true if you notice a change in your menstrual cycle. Though most period problems turn out to be nothing to worry about, it is always good to be safe.

See your provider if: