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Oestradiol (Oestrogen)
Oestradiol (E2) is the main and most potent form of oestrogen, made mainly by the ovaries. There is no single normal oestradiol number: what counts as healthy depends on your sex, where you are in your menstrual cycle, and whether you have reached menopause. Using Forth customer test results collected between January 2021 and June 2026 in the UK, this page explains what oestradiol does, what normal levels look like in pmol/L, and how those levels really change across life, rising through the reproductive years, peaking in the late forties, then falling sharply after menopause.
Written by Dr Thom Phillips
September 3, 2026
In this article:
Oestradiol at a glance
| What it is | The strongest of the three oestrogens (E1, E2, E3), made mainly by the ovaries. |
| Typical premenopausal range | Roughly 45–854 pmol/L, shifting across the menstrual cycle |
| After menopause | Levels fall sharply. Forth’s post-menopausal median is around 28 pmol/L without HRT. |
| When to test | Often day 3 or day 21 of the cycle, depending on what you’re checking. |
| In men | Present in small amounts (Forth male median ~82 pmol/L) and still important. |
What is oestradiol?
Oestradiol is a hormone, and the most active member of the oestrogen family. If you’ve been asked to check your “oestrogen”, it’s almost certainly oestradiol that’s being measured. It’s the form that dominates from puberty through to the menopause, and the one that drives the menstrual cycle, fertility and much of what we think of as reproductive health.
It’s produced mainly in the ovaries, specifically by the granulosa cells of a developing follicle and, after ovulation, by the corpus luteum. Smaller amounts come from the adrenal glands and from fat (adipose) tissue, where an enzyme called aromatase converts androgens into oestrogen. That last source matters more than it sounds: it’s why oestradiol doesn’t drop to zero after menopause, and why body weight can influence your levels. In pregnancy, the placenta becomes a major producer, and in men a small but meaningful amount is made by the testes and through the same aromatase conversion.
Oestradiol vs oestrogen: what’s the difference?
People use “oestrogen” and “oestradiol” as if they mean the same thing, and most of the time it doesn’t cause confusion, but they aren’t identical. Oestrogen is the family; oestradiol is one member of it. The family has three main hormones, and oestradiol (E2) is simply the dominant one during your reproductive years.
Oestrogen is an umbrella term for three related hormones. Oestradiol (E2) is the most potent, and the one a standard oestrogen blood test measures.
The three types of oestrogen (E1, E2, E3)
There are three oestrogens, and which one dominates depends on your life stage. This is one of the most common questions people ask — “how many types of oestrogen are there?” — and the answer explains a lot about why levels change so much over a lifetime.
| Oestrogen | Where it’s mainly made | When it dominates | Potency |
| Oestrone (E1) | Fat tissue and adrenals, converted from androgens | After menopause | Weakest |
| Oestradiol (E2) | Ovaries (and testes in men) | Reproductive years | Most potent |
| Oestriol (E3) | Placenta | Pregnancy | Weak |
The E2 that Forth measures is the key fertility and cycle marker. Oestrone takes over as the main circulating oestrogen after menopause, and oestriol is barely present unless you’re pregnant.
What is serum oestradiol?
“Serum oestradiol” simply means oestradiol measured in the serum: the liquid part of a blood sample once the cells are removed. You may also see “plasma oestradiol” (a very similar blood fraction) or “serum 17β-oestradiol”, which spells out the precise chemical form being measured. These aren’t different hormones or different tests in any way that changes your result; they’re just technical descriptions of where and how the measurement is taken. When a lab reports a “serum oestradiol level”, it’s reporting your oestradiol, full stop.
What does oestradiol do in the body?
Oestradiol is often described as the primary female sex hormone, and its reach is wide. It’s responsible for developing and maintaining the reproductive system, and it drives the changes of puberty.
Beyond reproduction, oestradiol helps protect bone density, supports cardiovascular health, influences mood and cognition, keeps skin and vaginal tissue healthy, and plays a role in how the body handles cholesterol. When levels fall, as they do at menopause, the effects show up across all of these systems, which is why the symptoms of low oestrogen are so varied.
Oestradiol’s role in the menstrual cycle
Across a single cycle, oestradiol rises and falls in a characteristic pattern. It climbs through the follicular phase as a follicle matures, peaks just before ovulation to trigger the release of an egg, dips, then rises again more gently in the luteal phase. Our own data follows exactly this shape.
Oestradiol across the cycle, from Forth data (median by cycle window): early follicular 127, rising to a peak around ovulation, then a luteal level near 357 pmol/L. LH, FSH and progesterone are drawn schematically for context — they’re not part of this dataset.
When are oestrogen levels highest and lowest?
Within a cycle, oestradiol is lowest during your period and in the early follicular phase, and highest in the day or two before ovulation. There’s often a smaller second rise in the luteal phase, which is why oestrogen can appear to “peak twice” across a month.
Across a lifetime, the pattern is broader still: levels build through the reproductive years, reach their highest average in the mid-to-late forties, then fall steeply through the menopause transition. Our data shows median oestradiol peaking in the 45–49 bracket before dropping sharply after 50.
Median oestradiol by age in Forth’s female data, with the typical 25th–75th percentile range shaded. The peak around 45–49 reflects the hormonal turbulence of late perimenopause, before levels fall.
Oestradiol in men
Oestradiol isn’t only a female hormone. Men produce it too, in smaller amounts, and it’s essential for bone health, libido and sperm production.
In Forth’s male data the median sits around 82 pmol/L and stays fairly steady across the adult age brackets. Problems tend to arise when it’s too high relative to testosterone rather than when it’s simply present (more on that below).
How is oestradiol controlled?
Oestradiol is regulated by a feedback loop between the brain and the ovaries, sometimes called the Hypothalamic-Pituitary-Gonadal (HPG) axis. The hypothalamus releases Gonadotrophin-Releasing Hormone (GnRH), which prompts the pituitary gland to release two more hormones: Follicular Stimulating Hormone (FSH) and Luteinising Hormone (LH). These act on the ovaries to stimulate follicle growth and oestradiol production. Rising oestradiol normally feeds back to damp down FSH and LH, but at mid-cycle the feedback briefly flips: a surge of oestradiol triggers the LH spike that causes ovulation. It’s a finely balanced system, which is part of why a single reading is only ever a snapshot.
What is a normal oestradiol level?
There’s no single “normal” oestradiol number, because the right range depends on your sex, where you are in your cycle, and whether you’ve been through menopause. That’s exactly why Forth applies different reference ranges to different results rather than one blanket figure. The tables below show the ranges we use.
Normal oestradiol range in pmol/L (and pg/mL)
In the UK, oestradiol is usually reported in pmol/L; US labs tend to use pg/mL. To convert, divide pmol/L by 3.671. Here are the Forth reference ranges in both units.
| Group | Low (pmol/L) | High (pmol/L) | Low (pg/mL) | High (pg/mL) |
| Men | 41 | 159 | 11.2 | 43.3 |
| Women — follicular phase (approx. d1–11) | 45 | 854 | 12.3 | 232.6 |
| Women — ovulation / mid-cycle | 151 | 1461 | 41.1 | 398.0 |
| Women — luteal phase (approx. d17–28) | 82 | 1251 | 22.3 | 340.8 |
| Women — post-menopause | 0 | 505 | 0 | 137.6 |
""A note on perimenopause: there isn't a separate “perimenopausal” reference range, because oestradiol in the transition swings unpredictably from high to low, sometimes within the same week. That's why symptoms and other hormones (like FSH) are used alongside oestradiol to build a picture, rather than relying on one value.""
Normal oestradiol levels by age
Averaged across the cycle, typical oestradiol rises gently through the reproductive years and peaks in the late forties before falling. The median figures from Forth’s female data give a real-world sense of this:
| Age | Median (pmol/L) | Typical range (25th–75th) |
| 18–24 | 128 | 86–237 |
| 25–29 | 145 | 95–266 |
| 30–34 | 154 | 98–278 |
| 35–39 | 167 | 105–306 |
| 40–44 | 192 | 117–354 |
| 45–49 | 228 | 105–458 |
| 50–54 | 164 | 46–412 |
| 55–59 | 56 | 19–248 |
| 60+ | 36 | 19–96 |
Oestradiol levels by cycle phase
If you’re still cycling, the phase you test in matters more than almost anything else. Forth’s medians by cycle window show how much the number moves:
| Cycle window | Median (pmol/L) |
| Early follicular (days 1–7) | 127 |
| Mid follicular (days 8–11) | 351 |
| Around ovulation (days 12–16) | 329 |
| Luteal (days 17–28) | 357 |
Oestradiol levels in perimenopause and menopause
As the ovaries wind down, oestradiol falls. In Forth’s data the premenopausal median is 173 pmol/L; after menopause it drops to 63 pmol/L overall, and as low as 28 pmol/L in post-menopausal women not taking HRT.
This decline is what drives many menopausal symptoms, from hot flushes to changes in bone density, and it’s the reason oestradiol testing is so often part of menopause and HRT conversations.
Low oestradiol: causes and symptoms
Symptoms of low oestradiol
Low oestradiol can show up as:
- irregular or missing periods
- hot flushes and night sweats
- difficulty sleeping
- low mood or anxiety
- vaginal dryness and discomfort during sex
- reduced libido
- brain fog
- a loss of bone density over the long term.
In younger women, persistently low oestrogen can also affect fertility.
What causes low oestradiol?
- Perimenopause and menopause: the most common cause. As the ovaries produce less oestradiol, levels fall and symptoms follow. This is a natural life stage rather than a problem to be fixed, though the symptoms are often very treatable.
- Surgical removal of the ovaries: removing the ovaries (oophorectomy) causes an immediate, steep drop in oestradiol, since the main production site is gone.
- Over-exercising and low energy availability (RED-S): very high training loads combined with insufficient fuel can suppress the hormonal signals that drive oestrogen production, sometimes stopping periods altogether. In our own data the picture is nuanced: median oestradiol in women training more than 15 hours a week wasn’t dramatically lower than in less active women. However, at the individual level, RED-S is a well-recognised cause of low oestrogen in athletes and warrants attention.
- Eating disorders and low body weight: because fat tissue contributes to oestrogen production, very low body weight and restrictive eating can lower oestradiol and disrupt or stop the menstrual cycle.
- Pituitary gland dysfunction: since the pituitary drives ovarian oestrogen production through FSH and LH, problems with the gland can lead to low oestradiol.
"If you're experiencing distressing symptoms, or periods have stopped, it's worth speaking to a doctor rather than self-diagnosing from a single reading. This guide is educational and isn't a substitute for medical advice."
High oestradiol: causes and symptoms
Symptoms of high oestradiol
Higher-than-expected oestradiol can cause:
- heavy or painful periods
- breast tenderness
- bloating
- mood swings
- headaches
- weight gain around the hips and thighs.
In our data, “High” labels became much more common in the mid-forties and after menopause. For example, more than a quarter of results in the 45–54 age range were labelled High, reflecting the hormonal swings of the transition.
How Forth oestradiol results split into Low, Healthy and High by age. The share of High results stays under 8% until the early forties, then climbs to around a quarter through the menopause transition before settling. Source: Forth customer data.
What causes high oestradiol?
Causes include:
- natural fluctuations of perimenopause
- HRT (see below)
- being significantly overweight, since fat tissue produces oestrogen
- certain ovarian conditions
- some medications or tumours (less commonly).
In Forth’s data, higher BMI was associated with a greater share of High results, consistent with the role of fat tissue in oestrogen production.
High oestrogen in men
In men, high oestradiol (often relative to testosterone) can cause reduced libido, erectile difficulties, breast tissue development (gynaecomastia) and mood changes. It becomes more common with age and with higher body fat, again because of aromatase converting testosterone into oestrogen.
What is oestrogen dominance?
“Oestrogen dominance” is a popular term for a state where oestrogen is high relative to progesterone, rather than high in absolute terms. It isn’t a formal clinical diagnosis, but the underlying idea — that the balance between hormones matters not just one number — is sound, and it’s a useful way to think about why symptoms don’t always track a single value.
How to manage your oestradiol levels
How to increase oestrogen levels naturally
If your levels are low, the right approach depends on the cause, so it’s worth understanding that first. General measures that support healthy hormone balance include:
- eating enough to meet your energy needs
- maintaining a healthy body weight
- managing stress and sleep
- including foods containing phytoestrogens, plant compounds found in soya, flaxseed, chickpeas and lentils that have a mild oestrogen-like effect.
These support overall balance rather than dramatically raising oestradiol, and they’re no substitute for medical treatment where that’s needed.
How to lower high oestrogen levels
Where high oestrogen is linked to body fat, gradual weight management can help, since less adipose tissue means less aromatase activity. Limiting alcohol, supporting liver health and eating plenty of fibre are also commonly suggested. If levels are high enough to cause symptoms, a doctor can help identify the cause and the right response.
Hormone replacement therapy (HRT)
For menopausal symptoms driven by falling oestradiol, HRT replaces some of the hormone the ovaries no longer make. Our data shows just how much difference it makes: post-menopausal women on HRT had a median oestradiol of 257 pmol/L, against 28 pmol/L for those not taking it: a nine-fold difference that brings levels back into a reproductive-era range.
Lifestyle, exercise and avoiding RED-S
Exercise is good for hormonal health, but there’s a threshold beyond which very high training loads without adequate fuelling can backfire, suppressing oestrogen and disrupting the cycle (RED-S). The goal is balance: training supported by enough energy intake, rather than training on empty. If your periods have become irregular or stopped alongside heavy training, that’s a signal to seek advice.
"A note on the pill: hormonal contraception changes what an oestradiol test tells you. In Forth's data, the combined pill roughly halved median oestradiol (79.5 vs 182 pmol/L in non-users), while progesterone-only methods barely changed it (171 pmol/L). If you're testing while on contraception, this context matters when reading your result."
The combined pill suppresses oestradiol; progesterone-only methods have far less effect. Source: Forth customer data.
How to test your oestradiol levels
Oestradiol is measured with a simple blood test and it’s one of the most common ways people check their hormonal health. You can have it done through your GP, or with an at-home finger-prick test like Forth’s, where you collect a small blood sample and post it to an accredited lab.
What is an oestradiol blood test?
An oestradiol blood test measures the amount of E2 circulating in your blood, reported in pmol/L. It’s the test people mean when they ask how to check oestrogen levels, what blood test shows oestrogen, or whether a blood test can show low oestrogen (it can, provided it’s taken and interpreted in the right context). A single sample tells you your level at that moment, which is why the timing of the test matters so much.
Oestradiol (oestrogen) tests
Forth offers several ways to check your oestradiol as part of a wider picture of hormonal health:
- Female Hormone Imbalance Blood Test checks oestradiol alongside other key hormones to help make sense of symptoms like irregular periods, low mood or fatigue.
- MyFORM® Female Hormone Mapping Blood Test tracks how your hormones, including oestradiol, change across your cycle rather than at a single point — useful when one snapshot isn’t enough.
- Oestradiol Blood Test: a focused finger-prick test measuring your oestradiol level, analysed by an accredited lab with results explained in context.
When to take the test
If you have a regular cycle, the best day to test depends on what you’re looking at.
- A day 3 test (counting the first day of your period as day 1) captures your baseline follicular level and is often used when assessing fertility or ovarian reserve.
- A day 21 test looks at the luteal phase, when oestradiol and progesterone should both be present, and is used to check whether ovulation has occurred.
If your cycles are irregular, there’s no reliable “right” day, which is where testing alongside symptoms and other hormones becomes important.
How to read your oestradiol results
Your result comes with a reference range and a label, typically Low, Healthy or High.
The key thing to understand is that the range is personalised to your context: a Forth result uses the range appropriate to your sex, cycle phase or menopause status, so “Healthy” means healthy for you, not against one universal number. If you’re reading a result and it doesn’t match how you feel, that’s not unusual.
How do I know if my oestrogen is low?
Lots of people ask how to tell if their oestrogen is low, or how they’d know when levels have dropped. The honest answer is that symptoms alone can’t confirm it.
The signs of low oestrogen (irregular or absent periods, hot flushes, night sweats, low mood, vaginal dryness, poor sleep, brain fog) overlap heavily with thyroid problems, low iron, stress and other conditions. They’re a good reason to look into it, but not a diagnosis. The only way to know your actual level is to measure it, in the right context, with a blood test.
HRT raises oestradiol substantially after menopause: a median of 257 pmol/L on HRT versus 28 pmol/L without — a nine-fold difference.
FAQs about Oestradiol (Oestrogen)
What is a good oestradiol level?
It depends entirely on context. For a premenopausal woman the range is wide (roughly 45–854 pmol/L) and shifts across the cycle; after menopause a much lower level is normal; and men sit lower again (around 41–159 pmol/L). There’s no single “good” number that applies to everyone.
Can low oestrogen cause weight gain?
Changes in oestrogen around menopause are associated with a shift in where the body stores fat, often towards the abdomen, and many people find weight harder to manage during this time. It’s rarely the only factor, but hormonal change does play a part.
Can low oestrogen cause headaches, palpitations or fatigue?
Fluctuating and falling oestrogen is linked to headaches (including hormonal migraines), palpitations and fatigue in some people, particularly around perimenopause. These symptoms have many possible causes, though, so they’re worth investigating rather than assuming.
Does oestrogen affect sleep?
Yes, falling oestrogen is one reason sleep often worsens around menopause, both directly and through symptoms like night sweats. Progesterone changes play a role too.
Can oestradiol levels be normal but symptoms still occur?
Absolutely. A single reading is a snapshot, oestradiol swings across the cycle and especially in perimenopause, and symptoms depend on the balance between hormones as well as absolute levels. A “normal” result alongside real symptoms is a common and valid reason to look further, ideally with a doctor.
What should my oestradiol level be on HRT?
There’s no single target. It depends on the type and dose of HRT and how you feel. In Forth’s data, post-menopausal women on HRT had a median around 257 pmol/L. Testing can help check that your level is where you and your doctor want it.
How often should I test my oestradiol?
That depends on why you’re testing. For tracking a cycle or fine-tuning HRT you might test more than once; for a general check, a single well-timed test is often enough. Your reason for testing should guide the timing.
Estradiol or oestradiol: which spelling is correct?
Both are correct: “oestradiol” is the British spelling and “estradiol” the American one. They refer to exactly the same hormone.
Oestradiol (Oestrogen) Tests
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Article references
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Emanuele, M. A., Wezeman, F., & Emanuele, N. V. (2002). Alcohol's effects on female reproductive function. Alcohol research & health : the journal of the National Institute on Alcohol Abuse and Alcoholism, 26(4), 274–281.
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Razzak, Z. A., Khan, A. A., & Farooqui, S. I. (2019). Effect of aerobic and anaerobic exercise on estrogen level, fat mass, and muscle mass among postmenopausal osteoporotic females. International journal of health sciences, 13(4), 10–16.
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Nappi RE, Chedraui P, Lambrinoudaki I, Simoncini T. Menopause: a cardiometabolic transition. Lancet Diabetes Endocrinol. 2022;10(6):442–456. https://doi.org/10.1016/S2213-8587(22)00076-6
This information has been medically written by Dr Thom Phillips
Thom works in NHS general practice and has a decade of experience working in both male and female elite sport. He has a background in exercise physiology and has published research into fatigue biomarkers.
Dr Thom Phillips
Chief Medical Officer