The Role of Estrogen in Your Body

Estrogen is the major sex hormone in cisgender women and it impacts more areas of your health than you may realize. It goes beyond fertility and sex-related functions to mood, bone strength, and even heart health.

Hormones are chemicals produced by your body that 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. You also have special hormone-specific receptors in your body that receive these chemical messages. (Think of receptors as locks and hormones as keys.)

The Different Types of 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, you have more estradiol in your bloodstream than you do other types of estrogen. Estradiol also has the strongest effect on your body's estrogen-specific hormone receptors.

Estradiol is produced mainly in your ovaries, and the amount they produce varies over the course of your monthly menstrual cycle. A small amount of estradiol is converted from another type of estrogen called 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 muscles.

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 your body continues to produce.

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. That's thanks to the placenta.

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 that aren't related to fertility. As a hormone, estrogen (mostly estradiol) acts on the parts of your body that have estrogen-specific hormone receptors. Estrogen is involved with numerous important functions throughout 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 don't 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, women can experience a significant increase in bone loss because the protective effect of 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. The hormone 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. In fact, complications of heart disease are the leading cause of death in women in the United States.
• Mood Management: Estrogen has a pretty significant effect on your brain. It is thought that estrogen affects how your brain structures are connected, how your brain cells communicate, and even the shape of your brain. Additionally, estrogen plays a big role in your mood because it has a very strong effect on a brain chemical called serotonin. Serotonin is a mood-balancing chemical and estrogen promotes its production. 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. 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 and their fluctuations can help you live better through all stages of your life.