why do girls go on their period ?

Answer 1

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 - their hips become curvier, they grow several inches in height, and their breasts grow larger. About 1 1/2 to 2 years after a girl's breasts begin to develop, she will get her first menstrual period (known as menarche, pronounced: meh-nar-kee). Menarche doesn't happen until all the parts of a girl's reproductive system have matured and are working together.

About 6 months or so before getting her first period, a girl might notice an increased amount of clear vaginal discharge. This discharge, which shouldn't have a strong odor or cause itchiness, is common and shouldn't worry a teen.

Girls are born with ovaries, fallopian tubes, and a uterus. The two ovaries are oval-shaped and sit on either side of the uterus in the lowest part of the abdomen called the pelvis. They contain thousands of eggs, or ova. The two fallopian tubes are long and thin - like hollow strands of spaghetti (only a little bit thicker). Each fallopian tube stretches from an ovary to the uterus, a pear-shaped organ that sits in the middle of the pelvis. The uterus, or womb, can enlarge quite a bit if it later becomes the home for a developing baby.

Down the Tubes

As a girl matures and begins to enter puberty, the pituitary gland produces chemicals that stimulate an egg in the ovary to "mature" and produce hormones called estrogen and progesterone. These hormones have wide effects on a girl's body, including physical maturation, growth, and emotions. The hormones also help prepare the girl's body to be ready for pregnancy.

About once a month, this tiny maturing egg leaves one of the ovaries - in a process called ovulation - and travels down one of the fallopian tubes toward the uterus. In the days before ovulation, the uterus, stimulated by estrogen, begins to build up its lining with extra blood and tissue, making the walls of the uterus thick and cushioned. If the egg reaches the uterus and is fertilized by a sperm cell, it attaches to the cushiony wall of the uterus, where it slowly develops into a baby.

During most of a female's monthly cycles, the egg isn't fertilized by sperm and does not attach to the wall of the uterus. The uterus sheds the extra tissue lining. The blood, tissue, and unfertilized egg leave the uterus, going through the vagina on the way out of the body. This is a menstrual period. This cycle will happen almost every month for several more decades - until a woman no longer releases eggs from her ovaries.

No Two Are the Same

Just as some girls begin puberty earlier or later than others, the same applies to periods. Some girls may begin to menstruate as early as age 9 or 10, but others may not get their first period until their mid to late teens. Some girls will find that their menstrual cycle lasts 28 days, while others might have a 21-day cycle, a 30-day cycle, or even a 45-day cycle.

Irregular periods are common in girls who are just beginning to menstruate - 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, or have two periods with hardly any time in between them, for example. Usually, after a number of months, the menstrual cycle will become more regular. Many women continue to have irregular periods into adulthood.

The amount of time that a girl has her period also can vary. Some girls have their period for just 2 or 3 days, while others may have it for up to 6 or 7 days or longer. The menstrual flow - meaning how much blood comes out of the vagina - can vary widely from person to person, too. All in all, an entire period consists of anywhere from a few spoonfuls to a 1/2 cup of blood. And even in the same girl, the flow and duration of her period may change from month to month. Much of the time, some changes in menstrual periods can be normal - but a doctor can help determine the cause of irregular, excessive, unusual, absent, or painful periods.

PMS and Pimples

Some girls may have physical or emotional changes that they notice around the time of their period as well. Some girls have menstrual cramps, which are pretty common - in fact, more than half of all women who menstruate say they have cramps during the first few days of their period. Doctors think that cramps are caused by prostaglandins, a chemical that causes the muscles of the uterus to contract. Depending on the person, these cramps can be dull and achy or sharp and intense. In either case, menstrual cramps tend to become less uncomfortable and sometimes even disappear completely as a girl gets older. In the meantime, many girls and women find that taking an over-the-counter pain medication like acetaminophen or ibuprofen can give them relief from their menstrual cramps. If these over-the-counter medications don't help, a girl should visit her doctor and discuss this with him or her.

Some girls and women find that they feel depressed or easily irritated during the few days or week before their period. Others may say that they get angry more quickly than normal, or that they cry more than usual. Others may notice cravings for certain foods. These types of mental changes may be the result of premenstrual syndrome, or PMS. PMS is related to changes in the body's - you guessed it - hormones. As hormone levels rise and fall during a woman's menstrual cycle, they can affect the way she feels, both mentally and physically. Some women, in addition to feeling more intense emotions than they usually do, may feel bloated or puffy because of water retention, and their breasts may become swollen and sore. Usually, PMS goes away soon after a period begins, but it can come back month after month.

Most girls and women with PMS can comfort themselves with the knowledge that their symptoms disappear when their period arrives. Doctors also recommend that women with PMS try to exercise to help make themselves feel better. It's not uncommon for girls to have an acne flare-up during certain times of their cycle; again, due to hormones. Fortunately, the pimples associated with periods tend to become less of a problem as girls get older.

The most important thing to remember about menstruation is that it's completely normal. With very few exceptions, almost every grown woman in the world has menstruated during her lifetime! A girl who joins the ranks of all those billions of women won't necessarily find her life changing that much - periods don't get in the way of exercising, having fun, and enjoying life. If you have any questions about periods, don't be shy about asking a parent, health teacher, doctor, or nurse. And don't forget about older friends or sisters who have had their period for awhile; they can also be helpful in piecing together the period puzzle.
http://library.adoption.com/Parenting-Girls/All-About-Menstration/article/6622/1.html

Answer 2

Don't worry, I had the same thing happen to me. It's completely normal. I started in the mid-summer, and for the first few months I was pretty irregular. I have run cross country for two years, and when I am running regularly, I can sometimes skip up to two or three periods. Heavy physical activities such as running can definitely cause you to skip a period or be pretty irregular. Just remember it's normal and you're not alone. Hope this helps! :)

Answer 3

because we have ever since the beginnnig of time. what happens is the uterus builds up a thick lining filled of tissue and blood in order to prepare for a possible baby. at the end of the cycle when ur body realizes there is no baby, the lining breaks down and the blood (and some small clots) comes out. then it starts all over again.

Answer 4

it is sexual maturity. All month, your uterus builds up a soft place to incubate a fetus. When ovulation occurs, and no fertilazation happens, the lining is shed, resulting in a period.

Answer 5

because we shed the lining in our uterus when our body knows we're not pregnant. that lining is to protect and nurture a fertilized egg cell if you did get pregnant.