The female reproductive system changes in other ways, as well. For instance, fibroids, which are usually benign tumors of the uterus (see "Uterine Conditions: Fibroids"), are more common in women between the ages of 30 and 40. Teens, meanwhile, are more likely than 30-yearolds to suffer from menstrual cramps. That's why it's so important to keep a handle on your uterine health by getting regular medical checkups and by doing periodic "internal" checks in which you decide what's normal and what's not.

During Adolescence
Adolescence is a unique space in time for many reasons. Ideally, it lays a healthy and hopeful foundation for adulthood. For girls entering puberty, understanding what it takes to be and stay healthy gynecologically can pay lifelong health dividends.

Menstruation typically begins between ages 11 and 14. At first, menstrual cycles tend to be irregular because most girls don't ovulate on an even cycle until two to three years after menstruation starts. Some periods are light, others very heavy; your period may last seven days this month and three days next month. Cycles could last three months, 28 days, or somewhere in between. It's a good idea for girls and teens to track their cycles on a calendar to help them predict when their next period is likely to occur.⁵

Most girls have no problems with their menstrual cycles, but others endure very heavy bleeding (menorrhagia) or very painful cramps (dysmenorrhea). If you have either problem with your menstrual period, you should be medically evaluated.

Teens and STDs
Sexually active teenage girls are at increased risk for sexually transmitted diseases (STDs) because they may have multiple sexual partners and may not insist on using condoms or use condoms incorrectly with each sexual act (including oral sex). Studies show that two-thirds of those who contract an STD are 25 or younger. One study found that one in five adolescent girls had an undiagnosed STD.⁷ The threat to long-term uterine health posed by STDs can't be overestimated.

Teens' STD risk is also elevated because of their physiology. Anatomically, girls have a greater risk of acquiring chlamydia, the second most common STD, because their reproductive system hasn't fully matured. The lining of the uterus is more exposed in adolescence, providing a bigger target for the bacteria that causes chlamydia. Ten to 20 percent of women diagnosed with chlamydia or gonorrhea develop pelvic inflammatory disease (PID), which can lead to chronic pelvic pain, infertility and potentially fatal ectopic pregnancy-the leading cause of pregnancy-related deaths for American women in the first trimester.⁸ As women age, the lining slides back into the uterus, where it is less vulnerable to infection. Thus, it may take fewer exposures when you're young to actually catch the disease than when you're older.⁹ That's one more argument for postponing sexual intercourse or, at the very least, using adequate protection against STDs.

Throughout Young Adulthood
Vigilance about your reproductive health is especially important during your 20s and early 30s. If you notice any unusual vaginal itching, discharge or odor, or if you've had an unexplained abdominal pain or fever, call your health care professional. Early treatment can often prevent the kind of infections that can lead to permanent infertility.

The best way to protect your fertility is to protect yourself against STDs by using condoms (male or female) consistently and correctly and seeing a medical professional at the first sign that anything is amiss.

If you decide to get pregnant, make an appointment with a health care professional for a complete physical before you start trying. There is much to learn and to do to make your pregnancy as healthy as possible. Don't worry if getting pregnant takes several tries. Even young, healthy couples have only a one-in-five chance of conceiving during any given menstrual cycle. In addition, a woman's fertility starts to slowly diminish as early as her late 20s and early 30s.¹⁰

About one-third of infertility cases stem from male-related factors, such as a low sperm count; one-third from female-related factors; and the remaining third by problems with both partners or unexplained causes.

Infertility treatments can range from losing or gaining weight under medical supervision, as well as lifestyle modifications such as limiting or curtailing an intensive exercise regimen, if you are engaged in one; to a variety of medical treatments. Conventional medical treatment options include: fertility drugs to stimulate ovulation; surgery to repair or unblock damaged fallopian tubes or to remove uterine fibroids; artificial insemination, in which sperm is concentrated and injected into the uterus through the vagina; and in vitro fertilization, in which eggs are removed, fertilized in a laboratory petri dish, allowed to grow for three to five days until they reach the several-cell stage, then implanted back into the womb.

Symptoms of menopause can occur any time from about age 35 to 60. That's because the gradually declining levels of estrogen and progesterone that mark the eventual end of your reproductive years don't happen over a steady curve. Rather, your hormone levels rise and drop like a roller coaster. That helps explain many of the irregular periods women experience as they approach menopause and the month-to- month changes in how they feel.

What's Happening and Why
Beginning in your mid-30s, your ovaries start shrinking as the number of egg follicles diminishes. Both the ovaries and their follicles become resistant to follicle stimulating hormone (FSH) and luteinizing hormone (LH), so your pituitary gland starts producing more and more of these hormones to keep up estrogen production. That's why an elevated FSH level is one indicator of perimenopause. At the same time, the ovaries are producing less progesterone (production of this hormone will stop altogether after menopause).

Progesterone prepares the uterus for a fertilized egg and signals the uterus to shed its lining if the egg isn't fertilized. But if the ovary isn't producing enough progesterone, the lining may continue to grow until a drop in the amount of estrogen brings on your period. A very heavy period is the result because the lining has grown so thick.

That's why symptoms will change as time goes by. Some are more prevalent in your 30s and 40s; others show up after menopause. Some are quite obvious and annoying (think hot flashes); others are silent but potentially crippling (think osteoporosis). As you get closer to menopause, you may experience additional menopause-related symptoms-urinary incontinence or frequent urinary tract infections, weight gain caused by a slowing metabolism, memory loss and hair loss (or gain).¹⁴ Some women-about 15 to 25 percent-experience no menopausal symptoms at all.¹⁵ The average age of menopause-defined as the day after 12 months of no periods-is about 51 years. Less than one percent of women experience natural menopause before age 40.¹⁶

It might surprise you, however, to learn that the average age for hysterectomy is 42.¹⁷ This may be because hysterectomy is often recommended as a treatment option for fibroids, which are most common for women in their 30s and 40s. But, this major surgery is rarely your only option. (See "If You Need a Hysterectomy" for more information about hysterectomy.)

Post-Menopause and Beyond
Just because your body can no longer become pregnant is no reason to put your gynecologic health on the back burner. This is the time of your life when your risk of gynecologic cancers-uterine, cervical and ovarian-increases. Nor does it mean that your uterus and ovaries have become superfluous. For some women, the uterus plays a role in their ability to have an orgasm and in urinary control.¹⁸

Continue to get regular gynecologic checkups, and see your health care professional if you experience:

Vaginal bleeding or spotting after you've stopped menstruating.¹⁹