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Estrogen

Medically Reviewed.Last updated on 04/14/2026.

Estrogen is a sex hormone that’s necessary for maintaining your sexual and reproductive health. Estrogen levels naturally fluctuate during different life stages and your menstrual cycle. Consistently high or low levels of estrogen may signal a condition that requires your healthcare provider’s attention.

Overview

What is estrogen?

Estrogen is a group of female sex hormones. Along with other hormones (like progesterone), estrogen plays a key role in female reproductive health. Males have estrogen, too, but in much lower amounts.

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Estrogen plays an important role in other body systems for males and females. This includes supporting heart, bone and brain health. Levels that are consistently low or high — when they’re not supposed to be — may signal an underlying condition.

Types

There are three major forms of estrogen:

  • Estrone (E1) is the primary form of estrogen that your body makes after menopause.
  • Estradiol (E2) is the primary form of estrogen in your body during your reproductive years. It’s the most potent (powerful) form.
  • Estriol (E3) is the primary form of estrogen during pregnancy.

Estrogen as medication

There are laboratory-made forms of estrogen. Healthcare providers may prescribe them to help with certain symptoms or conditions. Both menopause hormone therapy and combination birth control pills often contain estrogen.

Function

What does estrogen do for females?

Like all hormones, estrogen is a chemical messenger. It tells your body when to start and stop processes affecting your sexual and reproductive health. Estrogen has specific roles during different life stages and bodily processes for females.

Estrogen levels rise and fall throughout your life. The fluctuation is normal. For instance, it’s normal for estrogen levels to:

  • Rise during puberty and decline as you approach menopause
  • Rise during ovulation so that your body can prepare itself for pregnancy
  • Drop during your period because a pregnancy didn’t happen
  • Increase significantly throughout pregnancy, peaking in the third trimester
  • Fall dramatically after childbirth

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Puberty

Estrogen levels rise during puberty in females. The increase leads to physical changes, including further development (maturation) of your:

  • Breasts
  • Fallopian tubes
  • Ovaries
  • Uterus
  • Vagina

During puberty, estrogen also triggers changes in overall body composition, specifically adipose tissue (body fat) storage. It affects the shaping of your skeleton, too.

Menstrual cycle

Estrogen, along with other hormones, plays an important part in your menstrual cycle. These hormones coexist in a delicate balance to keep your periods regular.

Estrogen rises during the follicular phase of your cycle. It causes the lining of your uterus (the endometrium) to grow and thicken.

Fertility

Estrogen is highest in the days leading up to ovulation. This is your most fertile period. At the same time, estrogen thins your cervical mucus. This is the fluid sperm swim through to reach and fertilize the egg released during ovulation. These changes make it easier for you to become pregnant if you have unprotected vaginal sex.

Pregnancy

During pregnancy, estrogen (mainly estriol) plays a role in:

  • Fetal development
  • Uterine growth
  • Placental blood flow
  • Mammary gland development for lactation and breastfeeding

It also allows your uterus to contract to prepare for labor.

Sexual health

Estrogen makes it more comfortable to have intercourse. It keeps your vaginal walls elastic and lubricated, reducing pain associated with penetrative sex.

Menopause

Estrogen levels naturally drop during perimenopause, the time right before menopause.

The decrease in estrogen may lead to symptoms like vaginal dryness and hot flashes. The primary estrogen changes from estradiol (E2) to estrone (E1) during menopause.

What does estrogen do for males?

Estrogen seems to play important roles in males. This is mainly apparent because low or high levels of the hormone can cause issues.

In boys, estrogen deficiency limits the growth spurt in puberty due to the hormone’s effect on bones.

Estrogen also impacts male sexual and reproductive health. Too little estrogen can lead to a low sex drive. Too much of it can cause infertility, erectile dysfunction and enlarged breasts.

Other functions of estrogen

For everyone, estrogen regulates important processes in several body systems. It affects your:

  • Blood sugar levels
  • Bone density
  • Brain function, including your ability to focus
  • Cholesterol levels
  • Circulation and blood flow
  • Collagen production and moisture in your skin
  • Muscle mass and strength

Anatomy

Where is estrogen produced?

Your ovaries make most of your estrogen during your reproductive years. Your adrenal glands and adipose tissue (body fat) release estrogen, too. The placenta releases estrogen during pregnancy.

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If you’re male, your body converts small amounts of androgens (like testosterone) into estrogen.

Once it’s released, estrogen travels through your bloodstream until it reaches the part of your body that needs to be spurred into action. There, estrogen binds to a protein, called an estrogen receptor, that gets the process moving. You have estrogen receptors throughout your body.

Conditions and Disorders

What conditions are related to an estrogen imbalance?

Estrogen imbalances can play a role in several female health conditions, including:

  • Amenorrhea and oligomenorrhea (missed or irregular periods)
  • Breast cancer (this less commonly affects males, too)
  • Endometriosis
  • Fibrocystic breasts
  • Obesity
  • Osteoporosis (this less commonly affects males, too)
  • Ovarian cancer
  • Polycystic ovary syndrome (PCOS)
  • Primary ovarian insufficiency
  • Premenstrual syndrome (PMS)
  • Premenstrual dysphoric disorder (PMDD)
  • Turner syndrome
  • Uterine cancer (endometrial cancer)
  • Uterine fibroids and polyps
  • Vaginal atrophy

In females and males, estrogen imbalances can play a role in:

  • Alzheimer’s disease
  • Stomach (gastric) cancer
  • Infertility
  • Pituitary tumors
  • Schizophrenia
  • Sexual dysfunction

Scientists continue to research estrogen’s role in conditions affecting other body systems.

What are normal estrogen levels?

Estradiol is the main form of estrogen in your body once you get your period. In general, normal levels of estradiol for females include:

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  • Early follicular phase: 30 to 100 picograms per milliliter (pg/mL)
  • Late follicular phase: 100 to 400 pg/mL
  • Luteal phase: 50 to 150 pg/mL
  • Postmenopause: 2 to 21 pg/mL

After menopause, estrone is the main estrogen. In general, normal levels of estrone during postmenopause are 3 to 32 pg/mL.

For males, normal estradiol levels are:

  • Under the age of 18: Up to 36 pg/mL
  • 18 and older: 10 to 42 pg/mL

Interpreting estrogen test results can be complex. And normal ranges can vary from lab to lab. Your healthcare provider will explain your results and what they mean for you.

How do I know my estrogen level?

An estrogen test can measure your levels of estrone (E1), estradiol (E2) or estriol (E3). It’s a simple blood test. Your healthcare provider may recommend testing one or more of these estrogens if you have certain symptoms.

Since estrogen levels vary for many reasons and stages of life, your provider will explain what the results mean for your situation.

A note from Cleveland Clinic

Estrogen is a multifaceted hormone that plays crucial roles in female sexual and reproductive health. But it’s also essential for maintaining several aspects of everyone’s overall health. For example, you can thank estrogen for strong bones and clarity of thought.

Because this hormone is so important, imbalances can lead to several health issues. Reach out to your healthcare provider if you’re concerned about your estrogen levels.

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Medically Reviewed.Last updated on 04/14/2026.

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