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Estrogen: what it does in a woman's body
Estrogen is a group of sex hormones, made mainly by the ovaries, that drives puberty, the menstrual cycle, fertility and pregnancy. It also supports bone, brain, heart, skin and vaginal health. The three main types are estrone (E1), estradiol (E2) and estriol (E3). Estradiol is the strongest and the main estrogen before menopause; after menopause, estrone becomes the main one. Oestrogen is the British spelling of the same word.
Estrogen runs the cycle and affects brain, bone, skin and heart. Its three types, how levels change in perimenopause, and signs of low or high estrogen.
Estrogen in midlife: expectation vs reality
What people often expect
“Estrogen falls steadily through my 40s until it runs out”
What the evidence shows
In a large US study, average estradiol didn't start falling until about 2 years before the last period, then fell fastest around it and leveled off about 2 years after. Before that, estrogen in perimenopause often swings and can run higher than in younger women. After menopause, the body keeps making estrone from body fat and the adrenal glands.
What estrogen does in a woman's body
What does estrogen do to a woman?
Estrogen develops the breasts, uterus and vagina at puberty and shapes body fat and the skeleton. Each cycle it thickens the uterine lining and thins cervical mucus around ovulation, when it peaks. It keeps vaginal walls elastic and lubricated. Beyond reproduction, it affects blood sugar, bone density, focus, cholesterol, circulation, skin collagen and moisture, and muscle mass and strength.
Types of estrogen: estrone, estradiol and estriol
Estrone (E1) is the weakest, made mostly by body fat and the adrenal glands, and it's the only estrogen women keep making after menopause. Estradiol (E2) is the most potent and the main estrogen in the reproductive years, made mostly in the ovaries. Estriol (E3) rises in pregnancy and comes from the placenta. The body can convert estrone into estradiol when needed.
Learn more →Where estrogen is made in the body
The ovaries make most estrogen in the reproductive years; the adrenal glands and body fat also release it, and the placenta does in pregnancy. Estrogen travels in the blood and acts through estrogen receptors found throughout the body. Because body fat makes estrone, weight matters after menopause: in an analysis of eight studies, higher BMI went with higher estrogen levels and higher breast cancer risk.
Estrogen levels during the menstrual cycle
Estradiol is lowest early in the cycle and rises gradually. Two to three days before ovulation it climbs much faster to a peak, which triggers the LH and FSH surge that releases an egg. It dips after ovulation, rises again to the middle of the luteal phase, then falls back before your period. Labcorp's range is 12.5 to 166 pg/mL in the follicular phase and 85.8 to 498 around ovulation.
Learn more →Estrogen in perimenopause: swings before the drop
As periods become irregular, estradiol in cycles that still ovulate tends to rise, while progesterone after ovulation falls and more cycles skip ovulation. A study of daily urine samples found higher estrone levels in perimenopausal women than in younger women (76.9 vs 40.7 ng/mg creatinine). In SWAN, only 26.9% followed a slow decline; 31.5% rose and then fell steeply, and 28.6% stayed fairly flat.
Learn more →Estrogen after menopause
Once the ovaries stop releasing eggs, estradiol stays low: Labcorp's postmenopausal range is 6.0 to 54.7 pg/mL. Estrone from body fat and the adrenal glands becomes the main estrogen. Low estrogen causes hot flashes and vaginal dryness and speeds bone loss, raising the risk of osteoporosis. These changes are why HRT and vaginal estrogen are used after menopause.
Learn more →Estrogen and testosterone in women
Women and men make both hormones, but women have far more estrogen and men far more testosterone. In men, small amounts of testosterone are converted into estrogen. Women make testosterone in the ovaries, and unlike estrogen it doesn't drop suddenly at natural menopause: the NHS says the ovaries keep producing it for up to 20 years afterwards. Testosterone plays an important part in sexual desire.
Learn more →Estrogen as a medicine
Laboratory-made estrogens are used in menopause hormone therapy and in combined birth control pills. For menopause, estradiol comes as patches, gels, sprays and tablets, and low-dose estrogen is used in the vagina for dryness. If you have a uterus, estrogen therapy needs a progestogen to protect the lining. A few estrone-based products also exist, such as some hormone creams.
Learn more →Estrogen levels by the numbers
From the studies on this page
before the final period is when average estradiol starts to fall, in the SWAN study
2 years
Bar scaled to a 12-year reference span
of women in SWAN had estradiol that rose and then fell steeply around menopause
31.5%
85.8–498 pg/mL
6.0–54.7 pg/mL
Reference ranges differ between labs and test methods; Cleveland Clinic, for example, lists 2 to 21 pg/mL for estradiol after menopause.
Treating low estrogen: what works
HRT with estradiol
First stepThe most effective treatment for low-estrogen symptoms such as hot flashes and night sweats, and it helps prevent bone loss. Patches and gels avoid the extra clot risk of pills. With a uterus, you also need a progestogen.
Related guide →Vaginal estrogen
First stepLow-dose estrogen inside the vagina treats dryness, burning and pain during sex caused by low estrogen, and you can use it for as long as you need it.
Related guide →Bone care after menopause
Strong evidenceWeight-bearing and muscle-strengthening exercise, 1,200 mg of calcium a day from age 51, and enough vitamin D help protect bones as estrogen falls.
Related guide →Soy and other phytoestrogens
Limited evidencePlant estrogens are much weaker than your own. Soy isoflavone extracts modestly reduce hot flashes in trials, but they don't replace estrogen for bones or vaginal symptoms.
Related guide →
When to see a doctor about estrogen levels
Periods stop or become irregular before 45
See a doctor. This can be early menopause, or premature menopause before 40, which raises the risk of bone and heart problems; HRT is usually recommended.
More →Periods stop with weight loss, stress or heavy exercise
See a doctor. Low estrogen from functional hypothalamic amenorrhea needs checking and treatment.
Any bleeding after menopause
See a doctor. Bleeding a year or more after your last period always needs checking.
More →Hot flashes or vaginal dryness affecting daily life
Ask about HRT or vaginal estrogen; you don't need to wait for symptoms to become severe.
Estrogen: questions women ask
What is estrogen? A simple definition
A group of sex hormones, made mainly by the ovaries, that control puberty, the menstrual cycle and pregnancy and support bones, brain, heart and skin. The main types are estrone, estradiol and estriol.
What does estrogen do to a woman's body?
It develops the breasts and reproductive organs, thickens the uterine lining each cycle, helps release an egg and keeps the vagina lubricated. It also helps regulate cholesterol, blood sugar, bone density, muscle, skin moisture and focus.
Is oestrogen the same as estrogen?
Yes. Oestrogen is the British spelling and estrogen the American one; they mean the same hormones. You'll see oestrogen on NHS pages and estrogen on US drug labels.
What is the difference between estradiol and estrogen?
Estrogen is the family name; estradiol (E2) is one member of it, the strongest and the main one before menopause. Estradiol is also the estrogen in most HRT patches, gels and pills.
Related →What are normal estrogen levels in females?
They depend on the cycle phase. Labcorp's estradiol ranges are 12.5 to 166 pg/mL in the follicular phase, 85.8 to 498 around ovulation, 43.8 to 211 in the luteal phase and 6.0 to 54.7 after menopause. Other labs use different ranges.
Related →Estrogen versus testosterone: what’s the difference?
Both are sex hormones that women and men make. Women have much more estrogen, which drives the menstrual cycle; men convert small amounts of testosterone into estrogen. Women's ovaries also make testosterone, which supports sexual desire and continues for years after menopause.
When do estrogen levels drop?
Each month just before your period, and for good in the years around menopause. In SWAN, average estradiol began falling about 2 years before the last period and leveled off about 2 years after it.
What happens when estrogen is low?
Low estrogen can cause hot flashes, night sweats, vaginal dryness, painful sex, irregular or absent periods, trouble sleeping, dry skin, low sex drive and trouble concentrating. Over time it raises the risk of osteoporosis and heart disease. Menopause is the most common cause.
Related →What happens when estrogen is too high?
High estrogen, or too little progesterone to balance it, can cause breast tenderness, heavy or light periods, worse PMS, mood swings and a thickened uterine lining. Common causes include hormone medicines, excess body fat and heavy alcohol use.
Related →What are the functions of estrogen besides reproduction?
Estrogen helps maintain bone density, cholesterol and blood sugar levels, blood flow, muscle mass, skin collagen and moisture, and brain functions such as focus. That's why low estrogen after menopause can affect bones, skin and thinking.
How are estrogen levels tested?
Usually with a blood test for estradiol, sometimes urine or saliva. Levels change a lot through the cycle, so one result says little. NICE advises against using estradiol tests to diagnose perimenopause in women 45 and over.
Related →Sources
- Cleveland Clinic. Estrogen: hormone, function, levels and imbalances.
- MedlinePlus, US National Library of Medicine. Estrogen levels test.
- Cleveland Clinic. Estrone: function, hormone levels and testing.
- Randolph JF Jr, Zheng H, Sowers MR, et al. Change in follicle-stimulating hormone and estradiol across the menopausal transition: effect of age at the final menstrual period. J Clin Endocrinol Metab. 2011;96(3):746-54.
- Hale GE, Zhao X, Hughes CL, et al. Endocrine features of menstrual cycles in middle and late reproductive age and the menopausal transition classified according to the Staging of Reproductive Aging Workshop (STRAW) staging system. J Clin Endocrinol Metab. 2007;92(8):3060-7.
- Key TJ, Appleby PN, Reeves GK, et al. Body mass index, serum sex hormones, and breast cancer risk in postmenopausal women. J Natl Cancer Inst. 2003;95(16):1218-26.
- Labcorp. Estradiol (test 004515): reference range and clinical information.
- Santoro N, Brown JR, Adel T, et al. Characterization of reproductive hormonal dynamics in the perimenopause. J Clin Endocrinol Metab. 1996;81(4):1495-501.
- Tepper PG, Randolph JF Jr, McConnell DS, et al. Trajectory clustering of estradiol and follicle-stimulating hormone during the menopausal transition among women in the Study of Women's Health across the Nation (SWAN). J Clin Endocrinol Metab. 2012;97(8):2872-80.
- NHS. Hysterectomy: considerations.
- US Food and Drug Administration. Hormone replacement therapies can help women with bothersome menopausal symptoms.
- NICE. Menopause: identification and management (NG23). Updated 2024.
- Vinogradova Y, Coupland C, Hippisley-Cox J. Use of hormone replacement therapy and risk of venous thromboembolism: nested case-control studies using the QResearch and CPRD databases. BMJ. 2019;364:k4810.
- NHS. Types of hormone replacement therapy (HRT).
- NHS. When to take hormone replacement therapy (HRT).
- Office on Women's Health, US Department of Health and Human Services. Menopause and your health.
- Taku K, Melby MK, Kronenberg F, et al. Extracted or synthesized soybean isoflavones reduce menopausal hot flash frequency and severity: systematic review and meta-analysis of randomized controlled trials. Menopause. 2012;19(7):776-90.
- National Center for Complementary and Integrative Health. Soy: usefulness and safety.
- NHS. Early or premature menopause.
- Gordon CM, Ackerman KE, Berga SL, et al. Functional Hypothalamic Amenorrhea: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2017;102(5):1413-1439.
- NHS. Postmenopausal bleeding.
- NHS. Oestrogen tablets, patches, gel and spray: about.
- Cleveland Clinic. Low estrogen: causes, symptoms, diagnosis and treatment.
- Cleveland Clinic. High estrogen: causes, symptoms, dominance and treatment.
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