Health care

What Is the Role of Estrogen in Your Body?

Hormones are chemical messengers in your system that help to control and coordinate the way your organs and cells function. Hormones are produced by special glands in your body that release the hormones once your brain sends a corresponding signal. Special receptors binding to specific hormones receive these chemical messages.

Different hormones are related to different organs. Those taking part in reproduction and the development of sex organs are known as sex hormones, or sex steroids. The primary sex hormone in women is estrogen.

Types of Estrogen

In a woman’s body, there are three major types of estrogen (estradiol, estrone and estriol) that occur naturally, and whose amounts may vary from one to another during her lifetime.


During your reproductive period, that starts just before your very first menstruation and lasts until your menopause age, the primary estrogen in your body is known as estradiol, or E2. According to research, the amounts of estradiol in your bloodstream in your childbearing years tend to be higher than the other types of the hormone. In addition, the effect that estradiol has on estrogen receptors is the strongest among all the types of estrogens.

Estradiol is biosynthesized from cholesterol. This hormone is mainly produced within the follicles of your ovaries, and its amount may vary throughout your menstrual cycle. The sources of estradiol also include other endocrine and nonendocrine tissues, as well as a type of estrogen called estrone, which is converted to estradiol by the enzyme 17β-hydroxysteroid dehydrogenase.


Another type of estrogen present in your body is estrone (E1), which is the second most common after estradiol during your childbearing period. Estrone’s effect on your estrogen specific hormone receptors is also weaker than that of estradiol.

Small quantities of estrone are produced in your ovaries. However, the main source of estrone is another type of sex hormone called androgens. The androgens are converted to estrone through a special biochemical process – aromatization, which mostly occurs in your body fat and in your muscle. When your ovaries are no longer capable of producing hormones, i.e. in menopause, estrone becomes the only estrogen naturally present in your body.


Estriol, or E3, is a minor sex hormone in a woman’s body, whose levels in women who are not pregnant are almost undetectable. Once you get pregnant though, the levels of all types of estrogen in your body increase, and the levels of estriol increase the most. During pregnancy, the hormone is produced by the placenta, which makes it the most produced estrogen in the body by far. However, due to a high rate of metabolism and excretion, the circulating levels of estriol are more or less the same as those of estradiol and estrone.

Although estriol provides the weakest effect on your estrogen receptors, compared to other estrogens, this hormone plays an important role in your body during your pregnancy period. For instance, it helps to promote fetal growth and prepare your breasts for lactation.

What Is the Role of Estrogen in Your System?

As it was mentioned above, estrogen is the major sex hormone in a female body, which means it has a number of important functions, even when you are not pregnant. Estrogens, mainly estradiol, affect those parts of your body that have estrogen receptors. A more detailed description of estrogen’s role in your body is given below.

Female Puberty and Reproductive Anatomy

The hormone estrogen is responsible for the development of female secondary sexual characteristics during puberty period, which implies the development of breasts, widening of the hips, female fat distribution, as well as pubic and armpit hair growth. Estrogen is also essential for the maturation and continued development of female reproductive system, including the vagina and the uterus.

The changes in the body triggered by estrogen activity portend the first menstruation, indicating the beginning of the childbearing period.

Menstrual Cycle

Menstrual cycle is the regular natural change in the female reproductive system, whose main purpose is to produce oocytes and to prepare the body for pregnancy. This monthly occurs as a result of the rise and fall of hormones, and leads to the thickening of the lining of the uterus and the growth of the egg. If a woman does not conceive by the end of the cycle, the menstruation occurs due to the release of the lining.

The hormone responsible for thickening of the lining of the uterus during the menstrual cycle is estrogen.

Bone Health

Estrogens are essential for the development and maintenance of your skeletal system. The hormone is also responsible for the bone turnover and the protection against bone loss.

The quantities of estrogen in the body decrease significantly during menopause, which means that the protective effect of this natural hormone goes away increasing the risk of bone loss among elderly women. This may further result in osteoporosis and lead to even more serious consequences like a hip fracture.

Cardiovascular Health

Estrogen helps to maintain the health of the blood vessels by reducing the inflammation processes and regulating the cholesterol levels. Due to the activity of this hormone in the body, premenopausal women are unlikely to develop cardiovascular disease. However, in menopause, your heart is not protected by estrogen’s effect anymore, which increases your risk of heart disease development, to the point where complications of heart disease become one of the leading causes of death among elderly women.

Brain and Mental Health

Estrogen plays a significant role in female mental health. The hormone is considered to affect the shape of your brain, regulate the connection between your brain structures and influence the communication between your brain cells. It is also essential for mood management, due to its effect on serotonin – the chemical in your brain responsible for the mood balancing. Apparently, estrogen helps to increase the production of serotonin, meaning the lack of estrogen in your bloodstream may lead to the decrease of serotonin level, as well. Such a reaction of your brain caused by low estrogen levels is thought to contribute to the development of postpartum and menopausal depression in some women.

The Bottom Line

Estrogen is one of the primary female hormones that plays a very important role in the development of your body. Some of the major function of estrogen include shaping your figure, promoting your sexual development, developing your menstrual cycle, as well as preparing your body for pregnancy and even breastfeeding.

Besides, estrogen has some other important non-female functions necessary to maintain the health and strength of your body.

Sometimes, during your lifetime, the levels of estrogen get imbalanced, which may affect your mood and well-being. For instance, the changes in your period that occur in your reproductive years indicate the potential estrogen imbalance. Other examples of this condition include menopause and the menopausal transition. Any changes related to your menstrual cycle should be discussed with your doctor. Keep in mind that it is important to understand your hormones, in order to live a healthy and happy life.