10 Things Men Should Know About Female Hormones

You hear a lot about estrogen in discussions about women's hormones, and with good reason. Estrogen is the primary female sex hormone -- and it's responsible for a lot of different functions, including the growth of breasts and the maturation of the genitalia during puberty. It's also a big part of the menstrual cycle and influences a number of other functions in the body that have nothing to do with sex (more on that later). However, it's not just about the estrogen.

Progesterone also plays a part in the menstrual cycle, specifically helping to make the uterus suitable for a fertilized embryo. When a woman becomes pregnant, progesterone produced by her placenta helps support the growth of the fetus. The rise and fall of this hormone influences when a woman goes into labor and when she begins lactating. Women also have testosterone (although in lower amounts than men do). Testosterone has a lot to do with their sex drives, and it also influences bone and muscle density.

In addition to these three major hormones, there are even more hormones secreted by the pituitary gland that influence and regulate the menstrual cycle. No wonder things are so complicated.

When you start dating and get close enough to discuss intimate details with a woman, you'll eventually learn specific things about her that are related to her hormones, such as how her menstrual cycle influences her behavior and mood. But if you start dating another woman, you will soon learn a basic truth: Hormones are not the same in every woman. For you, this means that what works for one woman doesn't necessarily work for another. One may have the stereotypical moodiness and food cravings during that time of the month, while another doesn't seem to act any differently.

While all healthy women have the same hormones, levels of these hormones not only rise and fall each month in a complex pattern based on their menstrual cycles, they also vary based on the age of the woman and on the woman herself. During her reproductive years, for example, a woman may have anywhere from 50 to 400 picograms per milliliter (pg/ml) of estrogen in her blood [source: Nussey, Whitehead].

These variances are important to keep in mind when interacting with any woman: Don't assume that you know everything about her hormones just because you've been in a previous relationship!

Some people, including medical professionals, have dismissed premenstrual syndrome (PMS) as legitimate disorder. They say it's a convenient excuse for women to act cranky while eating junk food and lying around. However, many in the medical community recognize PMS as legitimate; it's experienced by three out of every four women. Nobody knows exactly what causes PMS, other than the fluctuations of hormones and chemical changes in the brain.

There can be a wide range of symptoms, in addition to food cravings and mood swings; some women also experience insomnia, headaches and intestinal distress. Most of the time, these symptoms go away once their period actually begins. Exercising, eating healthy foods and taking medications for the pain can help. Some women, however, experience an extreme, even debilitating type of PMS known as PMDD (premenstrual dysphoric disorder).

PMDD causes severe emotional symptoms such as high anxiety, anger and irritability beyond what is considered typical for PMS. Sometimes treatment is necessary and may include birth control pills or even antidepressants. It's important to note that some doctors believe that PMDD is a separate mental disorder.

Many women have little-to-no PMS symptoms at all. Recognizing what constitutes normal PMS symptoms in the woman in your life can help everyone manage a potentially difficult time.

If you paid attention during your sex ed classes, you may recall that the menstrual cycle is supposed to last 28 days. In the middle of the cycle, the ovary releases an egg. If that egg is fertilized, it will ultimately implant itself in the uterus and become an embryo. If the egg is not fertilized, the uterus sheds the lining it has built up. That shedding is the "period," and it lasts about seven days. If the menstrual cycle can be determined through this schedule, then women should always know when they're getting their periods, right? So why does your girlfriend occasionally send you to the store at night to buy her tampons?

Those numbers are just averages. Some women have longer menstrual cycles than others. Some women have periods that last just a few days, while others have periods that last for a full week. To complicate matters further, their cycles and period lengths can change over time and can be influenced by a wide variety of things, such as medication, exercise habits and stress. Many women have a general idea of when they're supposed to get their periods, but these complexities are part of why birth control pills were invented. The pill suppresses ovulation entirely and controls the cycle with artificial hormones. It not only reduces her chances of getting pregnant to almost none (when taken correctly), it also provides regularity.

You thought that hormones went crazy during puberty -- or during "that time of the month" -- but everything changes when a woman gets pregnant. HcG (Human Chorionic Gonadotropin) is a hormone made only by the cells of a forming placenta. Pregnancy tests are actually checking for the presence of it. Levels of this hormone rise rapidly during the first trimester as the placenta grows, which is also why there's morning sickness. HcG makes women more susceptible to illness by suppressing their immune systems (so their bodies don't reject their babies).

Estrogen and progesterone play very active roles. Estrogen does everything from stimulating a pregnant woman's breasts to grow and the baby's organs to develop, to giving mom a runny nose and sensitive skin. Progesterone does things like regulate placental function and allow the uterus to expand. This can also mean heartburn and indigestion. These hormones actually trigger other hormones as well, and these are a mere fraction of the changes that occur during pregnancy.

Some women are lucky enough not to experience any of the negative side effects of pregnancy hormones, but most have at least some of them. Pregnancy is an amazing feat of the female body, but be forewarned: The hormones involved can really wreak havoc during this time.

Estrogen and progesterone are always associated with women. But just as women have testosterone (the dominant "male hormone"), men have "women's hormones" -- just in smaller amounts. Estrogen is actually pretty close to testosterone from a chemical perspective. In men, estrogen is made from testosterone by an enzyme called aromatose. It contributes to the regulation of the male reproductive system and also influences male behavior. Estrogen tends to increase in men as they age, while testosterone levels decrease.

An estrogen imbalance in men can cause problems. Sometimes the increase results from obesity, because estrogen is made in fat cells, as well as in other places in the body. Men with conditions such as diabetes, prostate cancer and heart failure have been found to have high or low levels of estrogen -- so maintaining hormonal balance is important. Progesterone in men actually helps to regulate estrogen levels, which is why men found to have an estrogen/testosterone imbalance might be prescribed a progesterone supplement.

At its most basic, menopause just means that a woman stops being fertile. Technically, a woman is said to be "post-menopausal" if she has gone for 12 consecutive months without a period. Most of us hear about the negative side effects of menopause like hot flashes, night sweats and heart palpitations. Women dread going through the change because they've heard the horror stories. Of course, all of this is due to hormones, or more specifically, a reduction of the ovaries' hormone production.

You may not realize that menopause is actually a gradual transition -- it's not like turning off a switch. It also varies greatly depending on the woman, like everything else. Some women pass into menopause with relative ease. A woman beginning menopause is said to be in perimenopause, when the production of estrogen and progesterone starts to fluctuate and become irregular. Their periods also fluctuate in regularity and duration. Perimenopause generally starts for women in their late 30s or early 40s and can last for years. Hot flashes and other menopausal side effects can be extremely uncomfortable or even debilitating. Some women take medication or herbal supplements to help.

We mentioned a few pages back that men can have problems due to estrogen imbalances, so it stands to reason that estrogen and other hormones need to remain balanced in women as well. Of course, there's a wide range of normal depending on the person. The biggest culprit is estrogen; too little or too much can lead to serious health problems.

When estrogen levels get low, women lose bone density and have an increased risk of osteoporosis and bone fractures. They may also have a higher risk of heart disease due to raised cholesterol levels. While lowered estrogen is a normal part of menopause, some women experience imbalances due to premature ovarian failure (POF) -- menopause before the age of 40. Hormone replacement therapy (HRT) can help with this and other health issues associated with low estrogen, although in recent years HRT has gotten some criticism for other potential side effects, such as blood clots. On the other end of the spectrum, estrogen can also cause some forms of breast cancer to grow once established. This is known as a hormone-receptor-positive cancer, and patients may be prescribed anti-estrogen therapy.

Despite the fact that they're called "sex hormones," we almost got through this list without really mentioning sex ... until now. A woman's sex drive is already somewhat more precarious than a man's. For example, it typically takes more to get her in the mood than just viewing an attractive body. But how much of this has to do with hormones?

Women's hormones do figure prominently in a healthy libido; many women who have sexual dysfunction (which includes a lack of sex drive and sexual arousal) also have lowered estrogen levels. However, there are many other factors that affect libido -- it's not just about the hormones. These might include other health conditions, certain medications or lifestyle factors like drug or alcohol abuse. Sexual dysfunction in women can also be linked to a lack of intimacy, depression or body image issues. Treating it can be a challenge because there are so many possible causes.

However, it's also perfectly normal for a woman's libido to change over the course of her lifetime. When hormones are surging during adolescence, both men and women have higher libidos. As those hormone levels stabilize, a woman's libido is more likely to do the same. Then it could decrease as she matures and adds in environmental factors like birth control and job stress. And as we've mentioned, libido often goes down during menopause. But post-menopausal women may experience an increase in their libido once their hormones level off again.

After reading through this list, you may think that women are pretty much slaves to their hormones -- especially since the changes that they bring about throughout a woman's life can come with some nasty side effects. It's also true that "being hormonal" is often used as an excuse for a woman to act unlike her normal self. A 2009 study conducted at Hertfordshire University in England claimed that the "intense emotions" associated with PMS might be to blame for compulsive shopping [source: Daily Mail]. PMS has even been used successfully as a murder defense.

Put simply: Hormones are chemical signals that play a part in all of our body functions. While extreme hormone imbalances can definitely play a role in mental stability and overall behavior, simple PMS isn't likely to be the culprit. In other words, PMS might make women crave chocolate, but blaming it as the sole cause for a criminal act like murder is probably taking things too far. Women aren't slaves to their hormones any more than men are (that, after all, would imply that all they do is think about sex). Knowing more about the complexities of women's hormones, however, can only help men better understand the opposite sex.