What Is Estrogen and What Does It Do?

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Are you feeling hungry, tired or stressed? Did you know that there's a hormone or a hormone imbalance behind that feeling?

Hormones are chemicals produced by your body. They act as messengers that help control and coordinate how your body works and responds to your environment. You have special glands in your body that produce and release hormones when signaled by your brain. And you have special hormone-specific receptors in your body that receive these chemical messages.

The hormones that are involved in reproduction and the development of your sex organs are called the sex hormones.

In women, the major sex hormone is estrogen.

More Than Just One Estrogen

Your body produces three different types of estrogen. During your lifetime, the amounts of each of these different estrogens will change.

  • Estradiol (E2)Estradiol is the major estrogen in your body during your childbearing years. This is the time from just before your first period until your last period or menopause. During this time, the measured amount of estradiol in your bloodstream is more than the other types of estrogen. Estradiol also has the strongest effect on your body's estrogen specific hormone receptors. Estradiol is produced in your ovaries. The amount of estradiol produced by your ovaries varies over the course of your monthly menstrual cycle. Although most of your estradiol is produced by your ovary, a small amount is produced from another type of estrogen, estrone.
  • Estrone (E1): Estrone is the second most common type of estrogen produced by your body during your childbearing years. It also has a weaker effect than estradiol on your body's estrogen specific hormone receptors. Estrone is primarily made from another type of sex hormone in your body called androgens. A special biochemical process called aromatization changes the androgen into estrone. This process happens mostly in your body's adipose tissue or fat cells and in your muscle. Only a small amount of estrone is produced by your ovary. In menopause, when your ovaries stop producing hormones, estrone is the only type of estrogen produced by your body.
  • Estriol (E3): Estriol is typically known as the estrogen of pregnancy. It is present only in a very small—almost undetectable—amount in your bloodstream when you are not pregnant. Of all the types of estrogen, it has the weakest effect on your body's estrogen receptors. Although all types of estrogen levels increase when you are pregnant, estriol levels increase the most. The placenta is responsible for this marked increase in estriol production during pregnancy. Estrogen plays many important roles in pregnancy, from promoting fetal growth and development to preparing your breasts for lactation.

The Role Of Estrogen In Your Body

In its role as the major sex hormone in your body, estrogen does some pretty important things even when you aren't pregnant. As a hormone, estrogen (mostly estradiol) acts on the parts of your body that have estrogen specific hormone receptors. Here are some of the important things estrogen is involved with in your body:

Sexual development: Estrogen is responsible for the growth and continued development of your reproductive anatomy including your vagina and uterus. It also is responsible for the development of your breasts and the growth of your pubic and armpit hair during puberty.

Together these changes signal the upcoming arrival of your first menstrual period which marks the beginning of your childbearing years.

Your menstrual cycle: The underlying purpose of your menstrual cycle is to prepare your body for pregnancy. When you do not get pregnant during a monthly cycle, your uterus sheds its lining and you get your period. Estrogen is the hormone responsible for building up the lining of your uterus every month in preparation for pregnancy.

Bone development and health: Estrogen plays an important role in the healthy development of your bones. It also regulates bone turnover in your adult bones and protects against bone loss.

In menopause, when estrogen levels fall, there is a significant increase in bone loss because the protective effect of your body's own estrogen is gone. This dramatic increase in bone loss can lead to osteoporosis, which puts you at greater risk for a hip fracture.

Heart health: Estrogen helps protect against heart disease. Estrogen does a lot of good things in your body to help keep your blood vessels healthy, including decreasing inflammation and controlling your cholesterol levels. Taken all together, the positive effect of estrogen on the prevention of heart disease is significant in premenopausal women. In menopause, when the protective effect of estrogen is gone, there is a steady increase in heart disease in women. So much so that the leading cause of death in women in the US is from complications of heart disease.

Mood management: Estrogen has a pretty significant effect on your brain. It is thought that estrogen effects how your brain structures are connected, how your brain cells communicate, and even the shape of your brain. Estrogen also has a big role in your mood. It has a very strong effect on one of your brain chemicals called serotonin. Serotonin is the mood balancing chemical in your brain. It turns out that estrogen promotes the production of serotonin in your brain. That means when your estrogen level is low your serotonin level will decrease as well. The effect of this is very significant in some women. It is thought that this low estrogen-related drop in serotonin production contributes to postpartum and menopausal depression.

A Word From Verywell

Estrogen is a very important hormone in women. Not only does it shape your figure and impact your menstrual cycle, it also gives you the ability to have children and even breastfeed those children. Beyond these uniquely female things, it does a lot of behind the scenes work to keep your body strong and healthy.

At times in your life when your estrogen levels are imbalanced, you probably will not feel like yourself. During your reproductive years, changes in your period are a good indicator of a potential estrogen imbalance. Menopause and the menopausal transition are by definition times of estrogen imbalance. Be sure to discuss any changes in your menstrual cycle with your healthcare provider. Understanding your hormones will help you live very well through all stages of your life.

Sources:

Barth, C., Villringer, A., & Sacher, J. (2015). Sex hormones affect neurotransmitters and shape the adult female brain during hormonal transition periodsFrontiers in Neuroscience9, 37. http://doi.org/10.3389/fnins.2015.00037

Pérez-López, F. R., Larrad-Mur, L., Kallen, A., Chedraui, P., & Taylor, H. S. (2010). Gender Differences in Cardiovascular Disease: Hormonal and Biochemical InfluencesReproductive Sciences (Thousand Oaks, Calif.)17(6), 511–531. http://doi.org/10.1177/1933719110367829

Shapiro, M. (2012). Menopause practice: A clinician’s guide, 4th edition. Canadian Family Physician58(9), 989.

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