Estrogens are a group of steroid hormones that regulate reproductive development, menstruation, pregnancy, bone health, brain function, and other processes in the body. Estrogen is present in people of all sexes, although its levels and effects vary. The three main naturally occurring estrogens are estradiol, estrone, and estriol.
Estrogen Hormones at a Glance
| Estrogen | Also called | Main role or source |
|---|---|---|
| Estradiol | E2 | Main estrogen during the reproductive years; produced mainly by the ovaries |
| Estrone | E1 | Weaker estrogen; becomes the main estrogen after menopause |
| Estriol | E3 | Increases substantially during pregnancy; produced mainly by the placenta |
What Does Estrogen Do?
Estrogen affects reproductive organs, bones, the brain, metabolism, and other parts of the body. Its roles include:
- Starting and supporting puberty
- Supporting breast and reproductive-organ development
- Regulating the menstrual cycle
- Helping release an egg during ovulation
- Thickening the uterine lining during the menstrual cycle
- Supporting pregnancy
- Maintaining bone strength
- Affecting cholesterol, blood sugar, brain function, and muscle health
- Supporting sexual function and libido
Estrogen also has roles in males, including bone maintenance, brain function, and sperm development. Males typically produce estrogen when some testosterone is converted into estradiol.
Where Is Estrogen Produced?
In people with ovaries, the ovaries produce most estrogen before menopause. Smaller amounts come from:
- Fat tissue
- The adrenal glands
- The placenta during pregnancy
In males, the testes and other tissues produce smaller amounts of estrogen. After menopause, ovarian estrogen production falls substantially. Fat tissue and the adrenal glands continue to produce smaller amounts, particularly estrone. The adrenal precursor DHEA is one route into that pathway, and it is sold over the counter as a supplement; this is a DHEA supplement example on Amazon, with the dose and ingredient list on the page.
What Are the Main Types of Estrogen?
Estradiol, or E2
Estradiol is the main and most biologically active estrogen during the reproductive years. It helps regulate ovulation, supports the uterine lining, and contributes to bone and brain health. Estradiol levels change throughout the menstrual cycle and fall during menopause.
Estrone, or E1
Estrone is a weaker estrogen than estradiol. It is present in people of all sexes and becomes the predominant estrogen after menopause. The body can convert estrone and estradiol into one another.
Estriol, or E3
Estriol is present at relatively low levels outside pregnancy. During pregnancy, the placenta produces much more estriol. Estriol is therefore closely associated with pregnancy-related estrogen activity.
How Do Estrogen Levels Change?
Estrogen levels change throughout life and can fluctuate during the menstrual cycle.
- Puberty: Estrogen rises and contributes to reproductive development.
- Menstrual cycle: Estradiol rises and falls as ovarian follicles develop, ovulation occurs, and the uterine lining changes.
- Pregnancy: Estrogen production increases, and the placenta becomes an important source.
- Perimenopause: Estrogen levels may fluctuate unpredictably.
- Postmenopause: Ovarian estrogen production falls to lower levels.
These changes can affect menstruation, body temperature, vaginal tissues, sleep, mood, and bone strength.
What Happens When Estrogen Is Low?
Low estrogen can occur during menopause, after removal or failure of the ovaries, with some hormonal conditions, or because of certain medicines and health problems.
Possible effects include:
- Irregular or absent menstrual periods
- Hot flashes and night sweats
- Vaginal dryness or thinning
- Reduced sexual desire
- Sleep problems
- Mood changes
- Reduced bone density over time
Symptoms alone cannot confirm low estrogen. Many other conditions can cause similar symptoms. A healthcare professional may consider age, menstrual history, pregnancy status, medicines, and other hormone levels before recommending testing or treatment.
What Does High Estrogen Mean?
High estrogen can result from pregnancy, natural hormonal changes, hormone-containing medicines, certain ovarian or testicular conditions, liver problems, or increased conversion of other hormones into estrogen. The effects depend on the person and the cause.
Possible effects include:
- Irregular or heavy menstrual bleeding
- Breast tenderness
- Enlarged breast tissue in males
- Reduced fertility
- Changes in sexual function
A single estrogen result does not establish a diagnosis. Results must be interpreted in relation to the specific hormone tested, age, sex, menstrual-cycle stage, pregnancy status, and medicine use.
How Are Estrogen Levels Tested?
An estrogen test measures estrogen in a blood, urine, or saliva sample. The forms most often tested are:
- Estradiol, E2
- Estrone, E1
- Estriol, E3
Doctors may order testing to investigate irregular periods, fertility concerns, early or delayed puberty, menopause-related concerns, pregnancy-related questions, or symptoms that may be linked to hormone changes. Hormonal contraception and hormone therapy can affect test results, so patients should tell their healthcare professional about all medicines and supplements they use.
Is Estrogen Used as a Medication?
Prescription estrogen may be used to treat some menopause symptoms, vaginal dryness, low-estrogen conditions, and certain cancers. Estrogen is also used in some contraceptives and hormone therapies.
Estrogen treatment is not appropriate for everyone. Systemic estrogen can increase the risk of serious problems, including blood clots. When estrogen is used without appropriate protection in someone who still has a uterus, it can also increase the risk of endometrial cancer. Treatment decisions depend on medical history, age, symptoms, cancer risk, and the type and route of estrogen used. Estrogen should only be taken under the guidance of a qualified healthcare professional.
Estrogen Versus Progesterone
Estrogen and progesterone are different reproductive hormones.
- Estrogen helps develop reproductive tissues, supports ovulation, and thickens the uterine lining.
- Progesterone rises after ovulation and helps prepare and maintain the uterine lining for a possible pregnancy.
Both hormones work together during the menstrual cycle and pregnancy, but they are not interchangeable.
Bottom Line
For testing or treatment, the specific type of estrogen matters. Estradiol, estrone, and estriol vary with age, menstrual-cycle stage, pregnancy, menopause, medicines, and health conditions, so an estrogen result needs to be interpreted in context.