Hormones are specialized chemicals produced by your endocrine system that help control just about every function of your body, including growth, metabolism, and reproduction.

In women, female hormones are key components of reproduction, sexuality, and overall health and well-being.

Because female hormones play such major roles in women's bodies, women can sometimes feel as though their hormones are controlling them.

But if you have a good understanding of the role female hormones play, you will be better equipped to recognize abnormal hormonal imbalances and deal with the natural decline in female hormones that occurs with age.

Here’s a quick rundown — your ovaries, the organs that release an egg during ovulation, produce female hormones; the two main hormones are estrogen and progesterone.

The levels of both estrogen and progesterone drop off pretty dramatically after a woman stops ovulating at menopause, but the decline in estrogen is what’s responsible for most classic menopause symptoms.

Estrogen: The Hormone Behind Your Period

Estrogen is the female hormone that fluctuates over the course of a woman’s menstrual cycle. A gradual rise in the level of estrogen in the first two weeks of the menstrual cycle — called the follicular phase of the cycle — is what causes women to build up a uterine lining each month in preparation for pregnancy, and a drop in estrogen (and progesterone) is what causes women to have a menstrual period each month.

Estrogen is also an important factor in maintaining women's bone and cardiovascular health.

Girls begin producing estrogen at puberty, and estrogen production declines as a woman ages, until she isn't making enough to thicken the uterine lining and have menstrual periods. In addition to the end of menstruation, some signs of low estrogen levels are hot flashes and vaginal dryness.

Some women take estrogen hormone replacement therapy (HRT) around menopause or when there is another reason for estrogen decline (such as surgical removal of the ovaries). HRT can reduce symptoms of low estrogen levels and help slow age-related bone loss in women, but there are some health risks associated with taking HRT, such as increased risk for cancer. Ask your doctor about the risks and benefits of HRT for your specific situation.

Progesterone: Essential for Pregnancy

During a woman's childbearing years, progesterone levels rise during the second half of her menstrual cycle, after the monthly egg is released from her ovary. If she becomes pregnant, the progesterone level continues to rise, and helps keep the uterine lining thick for the developing baby. If she does not become pregnant, levels of progesterone fall, signaling the body to shed the uterine lining during menstruation.

If you have not had your uterus surgically removed (hysterectomy) and you have HRT, your doctor will likely recommend that you take progesterone in addition to estrogen to keep your uterine lining from growing too thick and to decrease your risk of endometrial cancer.

Progesterone, though essential for reproduction, sometimes produces annoying symptoms for women during the last two weeks before her menstrual period. These symptoms include bloating, breast tenderness, and acne. Sometimes a combination of physical symptoms and changes in mood regularly occur in the week before menstruation; this is often referred to as premenstrual syndrome, or PMS. PMS can often be managed by lifestyle changes — like exercising and eating a healthy diet — and over-the-counter medications, such as Motrin, Advil, or Midol Cramp (ibuprofen) and Aleve (naproxen).

Testosterone: It’s Not Just for Men

Another hormone, testosterone, is produced in low amounts in women, but is generally considered a male hormone. Elevated levels of testosterone may cause virilizing symptoms — meaning that some male physical characteristics may occur, such as abnormal, male hair growth patterns.

If your testosterone levels are abnormally high, it could be a sign of a health condition such as:

Polycystic ovary syndrome (PCOS)
Ovarian tumor
Tumor on your adrenal gland
Congenital adrenocortical hyperplasia

Too little testosterone can cause symptoms, as well. There is some evidence that declining levels of testosterone in older women and in women who have had their ovaries removed may be associated with declining sexual desire. One study showed that women who received testosterone therapy had improved sexual function, but there are still some questions about its safety and effectiveness.

Are You hCG Positive?

The hormone known as human chorionic gonadotropin, or hCG, is produced by the placenta of pregnant women. In fact, hCG is the hormone that is detected by a pregnancy test to confirm a pregnancy. During early pregnancy, hCG helps maintain the corpus luteum, which is the part of the ovary that produces progesterone after an egg is released. Levels of hCG increase until a woman is about 10 weeks pregnant, then they slowly decline throughout the rest of pregnancy. hCG is usually only produced by pregnant women, but it may also be produced by people who have certain health conditions, like germ cell tumors and trophoblastic disease, a rare disorder in which tumors grow in the cells that otherwise would grow in the placenta.

If you have concerns about your hormone levels, talk with your doctor. In some cases, your doctor may recommend a simple blood test to determine if your hormones are out of whack. Or she may refer you to an endocrinologist, a doctor who specializes in diagnosing and managing disorders that involve your hormones.

The Facts About Female Hormones