The female reproductive system is the organ system in girls and women responsible for maintaining the reproductive cycle. The organs and tissues in the system have specific roles, such as producing eggs (ovaries) and carrying a developing fetus (uterus).

The external structures of the female reproductive system are collectively referred to as the vulva. They include the mons pubis, labia and clitoris. These structures cover and protect the vaginal opening.

The vagina is the outermost internal reproductive structure in females. It is separated from the uterus, also known as the womb, by the cervix. The fallopian tubes attach to the upper corners of the uterus. Each one ends in a funnel-like area with finger-like fringes that wrap around, but do not completely connect with, the ovaries. The ovaries store, nurture and release the eggs and produce female sex hormones (e.g., estrogen, progesterone).

At some point during puberty, once the reproductive system has matured, the monthly menstrual cycle begins. At the beginning of the menstrual cycle, one of the ovaries releases an egg that travels into the fallopian tube. If it is not fertilized, it is expelled from the body along with blood and uterine tissue (endometrium) in the process called menstruation.

If a man’s sperm meets an egg in the fallopian tube, the egg may be fertilized. Once fertilized, the egg continues to travel through the fallopian tube and into the uterus, where it becomes implanted into the inner lining. It develops into an embryo and then a fetus. The fetus continues to grow and develop, cushioned by the amniotic fluid (fluid contained in the uterus during pregnancy to protect the fetus and regulate temperature) and nourished by the placenta (endometrium spongy structure that nourishes the fetus).

Around an average of about 280 days (about nine months) after fertilization, the fetus is ready to be born. The mucus plug in the cervical opening loosens, the walls of the uterus begin to contract, and the cervical opening begins to widen until it is wide enough for the infant to pass through. Once the infant passes through the cervix, it is pushed along the birth canal and out of the body.

A number of conditions may affect the reproductive system of female children and adolescents (e.g., urinary tract infections, yeast infections). If a child or adolescent displays any signs or symptoms of any condition affecting her reproductive system, a visit to a pediatrician is warranted.

The reproductive systems are the unique organ systems in each gender that allow a species to create further generations. The female reproductive system is responsible for the production of eggs (ova) and the support and nourishment of a developing fetus. The structures of the female reproductive system are located in the pelvis.

The external structures of the female reproductive system are collectively referred to as the vulva. The vulva surrounds and covers the vaginal opening and protects the internal reproductive structures. The mons pubis is the mound of fleshy tissue located to the front of the vulva. The labia are the outer and inner pair of skin folds located on the right and left side of the vulva. The outer labia (labia majora) are large, thick and fleshy. During puberty, pubic hair begins to grow over both the mons pubis and the outer surface of the labia majora. The inner labia (labia minora) are smaller. They directly flank the vaginal opening.

The clitoris is located at the point where the inner folds of the labia minor come together, towards the front of the vulva. This sensory organ is made of erectile tissue like the penis in males but is much smaller. It is covered by a small flap of skin (prepuce), similar to the foreskin in males.

The vaginal opening begins the passage toward the internal female reproductive structures. Most girls are born with a sheet of thin tissue called the hymen that partially covers the vaginal opening. This structure often tears or stretches after sexual intercourse for the first time, but it may not change at all. The hymen can also be separated before first intercourse, (e.g., due to stretching during sports). When it tears, it may bleed a bit, but there is usually little or no pain.

Beyond the hymen is the vagina, a hollow tube with muscular walls that allow it to expand and contract. It is lined with mucous membranes, which secrete mucus to protect and lubricate its surface. The vagina of an adult woman is typically around 3 to 5 inches (about 8 to 12 centimeters) long. It serves as the primary passage into (for semen released during sexual intercourse) and out of (for the expulsion of menstrual flow and the birth of an infant) the female reproductive system. During the birth of an infant, it is called the birth canal.

The vagina is connected to the cervix, which is the lower part of the uterus. The cervix provides protection by keeping most particles or foreign bodies that pass into the vagina out of the uterus. During pregnancy, a mucus clot forms over the cervical opening to prevent the contents of the uterus (e.g., the fetus, amniotic fluid) from passing into the vagina. The cervical opening is usually very small, but can expand widely for the delivery of an infant.

The uterus is also referred to as the womb. It is the strong, muscular, hollow organ where a fetus grows and develops. In adult women who are not pregnant, the uterus is usually about 3 inches (around 7.5 centimeters) long and 2 inches (about 5 centimeters) wide. During pregnancy, the uterus expands to accommodate the size of the growing fetus. By the end of the pregnancy, the average fetus is about 20 inches (51 centimeters) long and weighs about 7 pounds (3 kilograms).

Two slender tubes, called the fallopian tubes, attach to the upper corners of the uterus. At the opposite end of each tube is a funnel-like area with finger-like extensions that wrap around, but do not completely connect with, the ovaries. The interior of each fallopian tube is lined with tiny hairs that propel an egg from the ovary into the uterus. These tubes are very thin, and each one is about 4 inches (around 10 centimeters) long.

The ovaries are the female gonads. These small organs store, nuture and release eggs and, in conjunction with the pituitary gland in the brain, produce female sex hormones (e.g., estrogen, progesterone). There are two ovaries, located toward each side of the uterus. Each ovary of an adult woman is usually around 1.5 to 2 inches (about 4 to 5 centimeters) in length.

The primary function of the reproductive system – whether male or female – is to create a new generation and further propagate life. The female reproductive system supports and nurtures the fetus, and the male reproductive system is required to produce and supply the sperm to fertilize the egg (ova). The sperm and egg contain the genetic material of the parents and, when combined, form the genetic blueprint of the child.

When a female infant is born, an incredible number of immature eggs are present in her ovaries. These are all the eggs a female will possess in her lifetime. They cannot be replaced once they are used, damaged or destroyed. The eggs remain in an inactive state until puberty.

When a girl enters puberty, typically around age 10, certain hormones are produced by the pituitary gland. These hormones cause the ovaries to produce female sex hormones (e.g., estrogen, progesterone) and the girl begins to sexually mature. However, some children experience puberty earlier than their peers (precocious puberty).

At some point during puberty, once the reproductive system has matured, the monthly menstrual cycle begins. Girls begin menstruation at different ages, but the cycle usually begins somewhere around 12 or 13 years of age. However, it is not unusual for menstruation to begin as late as an age of 15 years. Whenever it occurs, the first period of menstruation is called menarche. Menstruation indicates the ability of a girl to become pregnant. A variety of conditions (e.g., eating disorders) and other concerns (e.g., weight issues, excessive physical activity) can cause problems with menstruation.

At the beginning of the menstrual cycle, estrogen stimulates the inner lining of the uterus (endometrium) to thicken with blood. This creates a nurturing environment for a potential fetus. As this occurs, one egg in each ovary matures, and one of these eggs is released into the nearby fallopian tube. This stage of the menstrual cycle is called ovulation.

If the egg is not fertilized, it dies and is expelled from the body with the menstrual flow. This tends to occur about two weeks after ovulation. The menstrual flow contains blood and sloughed tissue from the endometrium. The release of menstrual flow, which may be referred to as menstruation or a period, tends to last around three to five days. However, some girls menstruate for slightly longer or shorter periods.

A girl’s menstrual cycle tends to be irregular for the first two years as the body adjusts to puberty and new hormones. Once the cycle has become regular, it generally lasts around 28 days.

Sperm contained in a man’s semen fertilizes an egg. At ejaculation, between 0.05 and 0.2 fluid ounces (around 1.5 to 6 milliliters) of semen, containing between 75 and 900 million sperm, are released from a male’s penis. When this occurs inside the vagina during unprotected sexual intercourse, the sperm travel through the cervix and uterus and into the fallopian tubes. If a sperm meets with an egg in a fallopian tube, the egg may be fertilized. Only one sperm is necessary to fertilize an egg.

The fertilized egg (zygote) continues to travel through the fallopian tube and into the uterus. It grows and develops into a multicellular, fluid-filled form called a blastocyst. Once inside the uterus, the blastocyst burrows into the enriched endometrium, from which it absorbs nutrients. This process occurs about a week after fertilization. The nourished blastocyst eventually develops into an embryo. By the eighth week, the embryo grows and develops the major parts of the body (e.g., brain, stomach, heart).

The fetal stage begins around nine weeks after fertilization and continues until birth. The fetus is nourished by the placenta, a disc-shaped structure attached to the endometrium and connected to the fetus by the umbilical cord. The placenta also functions to produce a pregnancy hormone called human chorionic gonadotropin (hCG). This hormone helps support the developing fetus by providing information on the needs of the fetus to the rest of the body.

Around an average of 280 days (about nine months) after fertilization, the fetus is ready to be born. At this point, the head is typically angled downward and pressing against the cervix. When a woman’s water breaks, the mucus plug in the cervix loosens and is usually expelled through the vagina, along with the amniotic fluid. Contractions usually begin as oxytocin (a hormone from the pituitary gland) stimulates the uterine walls to contract. At the same time, the cervix becomes thinner and the opening of the cervix begins to slowly widen (dilate) until it is wide enough for the infant to pass through. This process, known as labor, varies greatly among women, lasting from a few hours to more than 24 hours.

After passing through the cervix, the infant is pushed along the birth canal and out of the body. The umbilical cord is still attached and is cut after delivery. Once the infant is delivered, the placenta, which has separated from the endometrium and is now called the afterbirth, is expelled in a similar manner.

There are a number of conditions that may affect the reproductive system of female children and adolescents. If a child or adolescent displays any signs or symptoms of any condition affecting her reproductive system, a visit to a pediatrician is warranted. Adolescent girls also benefit from regular gynecologic exams. Talking with a pediatrician can help determine when a girl should have her first gynecological exam. This depends on many factors, including the girl’s menstrual and sexual history.

Both the American Academy of Pediatrics (AAP) and the American College of Obstetricians and Gynecologists (ACOG) now recommend that adolescent girls see their primary care physician for preventive healthcare visits to discuss their reproductive health, and help establish an environment where they can feel comfortable discussing health concerns. Preventive health visits during adolescence can offer an opportunity for physicians to educate teen girls and their parents on what comprises normal puberty, menarche (a girl’s first period) and the menstrual cycle.

Problems with menstruation are common. Many girls and women experience cramps, or episodes of abdominal pain, that may range from dull to intense. These cramps are caused by the contractions of the uterine muscles and often occur during the first few days of menstruation. They usually do not last long and can often be soothed by a warm compress, bath or over-the-counter medications.

Premenstrual syndrome (PMS) is a combination of numerous symptoms that may occur in the week just before a girl or woman begins to menstruate. Most of these symptoms vanish once menstruation starts. PMS does not occur in all girls, although some who did not experience it in adolescence may develop it at a later age. Not all girls have the same symptoms, which may include:

• Acne
• Bloating
• Fatigue
• Backaches, headaches and/or sore breasts
• Constipation or diarrhea
• Food cravings
• Depression and/or irritability
• Difficulty concentrating or handling stress

Other menstrual problems include dysmenorrhea (very painful menstruation) and menorrhagia (menstruation with excessive bleeding). Oligomenorrhea occurs when a girl who is not pregnant and who had been menstruating normally for several years misses or has infrequent periods. Amenorrhea is the absence of a period in a girl who is not pregnant. It may be primary (no period by the age of 16 years) or secondary (halted menstruation in a girl who previously had normal periods). Amenorrhea may be caused by factors including excessive exercise (e.g., gymnastics, ballet) and hormonal conditions such as polycystic ovarian syndrome (PCOS). Other menstrual problems may result from similar causes.

Vaginal bleeding that is not associated with menstruation may be caused by a foreign body in the vagina (e.g., toilet paper), urethral prolapse (protrusion of urethral tissues into the vagina) or injuries. Examples of injuries that may cause vaginal bleeding include straddle injuries (e.g., falling onto a beam or bicycle frame) and sexual abuse trauma. Some sexually transmitted diseases (STDs) can also cause vaginal bleeding.

STDs are infectious diseases that are typically spread through sexual contact. The United States has high rates of STDs, which can often be prevented by the use of condoms during sexual intercourse. Many of these can affect fertility or can infect a fetus or infant during pregnancy or childbirth. There are a large number of sexually transmitted diseases, including:

• Gonorrhea
  
• Chlamydia
  
• Genital herpes
  
• Human papilloma virus (HPV), also called genital warts
  
• Human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS)
  
• Syphilis

Another serious infection is toxic shock syndrome (TSS). This is an uncommon condition that is most likely to occur when a tampon is left inside the vagina for too long. It is caused by the release of toxins from a bacterial infection and can cause fever, diarrhea, vomiting and shock. Tampon products contain warnings about TSS and provide information on how to prevent it, including frequent changes of tampons.

Pelvic inflammatory disease (PID) is another infection of the female reproductive system. This condition can spread throughout the entire reproductive system. PID may be caused by STDs, surgery or when naturally occurring bacteria in the vagina travel farther into the body. It requires treatment in order to prevent damage to the reproductive system that can cause fertility problems.

Other conditions that may affect the female reproductive system include:

• Vulvovaginitis. Irritation and inflammation of the vulva and vagina, causing redness and itching. This condition may be caused by irritating substances (e.g., soaps, bath oils), poor personal hygiene (e.g., poor toilet hygiene), and yeast infections (occurs when a fungus that is naturally present in the vagina [Candida] overgrows.
  
  
• Ovarian cysts. Common and usually harmless fluid-filled sacs in the ovaries. They may become large and cause pain as they press against nearby organs. They usually disappear without treatment.
  
  
• Polycystic ovarian syndrome (PCOS). A hormone disorder that causes numerous ovarian cysts due to the presence of too many androgens (male hormones). It may be first diagnosed during adolescence. PCOS can cause irregular or missed menstrual cycles, excessive weight gain and Acne, and it may put women at risk of infertility or diabetes.
  
  
• Labial adhesions. Occur when the labia stick together (adhere), partially blocking the vaginal opening. This occurs most commonly in infants and young children. It does not usually cause any symptoms but may increase the risk of a urinary tract infection. It is treated with estrogen creams applied to the labia.
  
  
• Ovarian torsion. Occurs when an ovary becomes twisted, blocking its blood flow. This may be caused by a disease or developmental problem and usually causes lower abdominal pain. It can result in infertility and typically requires surgical treatment.
  
  
• Endometriosis. Occurs when tissue from the inner lining of the uterus (endometrium) begins to grow elsewhere, such as in the ovaries or fallopian tubes. Symptoms include pelvic pain that can be severe and chronic, painful menstruation and abnormal bleeding. The causes of this condition are not known.
  
  
• Uterine fibroids. Benign (noncancerous) tumors that sometimes develop in a woman’s uterus. They may become large and compromise the health of the uterus and nearby organs. In such cases, severe symptoms (e.g., abnormal uterine bleeding, pelvic pain, bladder/bowel problems) can develop and prompt medical attention is necessary.

Preparing questions in advance can help patients and parents have more meaningful discussions with their physicians regarding their or their child’s treatment options. The following questions related to the female reproductive system may be helpful:

1. Does my/my daughter’s reproductive system appear to be developing normally?
   
   
2. What can I/my daughter do to keep my/her reproductive system healthy?
   
   
3. If I/my daughter have/has not had my/her first period yet, what can I do?
   
   
4. Are my/my daughter’s periods normal?
   
   
5. How long may it take for my/my daughter’s menstrual cycle to become regular?
   
   
6. When should I/my daughter go for my/her first gynecologic exam?
   
   
7. Can you recommend how to discuss sexually transmitted diseases, contraception and pregnancy with my daughter?
   
   
8. Should I/my daughter consider birth control pills or another form of contraception?
   
   
9. Can you recommend any local resources or support groups that deal with adolescent pregnancy?
   
   
10. What are the potential dangers of pregnancy at my/my daughter’s age?