All about menstruation

Picture a crowded hallway in your school between classes. People are rushing to class, locker doors are being flung open and slammed shut, and a girl is opening the door to the Girls' room.

Now freeze on that mental picture. Which of the following choices is a good description of you in that picture?

Chances are you can recognize yourself in choices a, b, or c - or some combination of the three. Menstruation (or a period, as it's often called) represents a major stage of puberty in girls; it's one of the many physical signs that a girl is turning into a woman. And like a lot of the other changes associated with puberty, menstruation can be confusing for girls (and guys). Some girls can't wait to start their period, while others may feel afraid or anxious. Others worry that they may never get it. Many teens of either gender don't have a complete understanding of a woman's reproductive system or what actually happens during the menstrual cycle - making the process seem even more mysterious. 

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 - 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.