FSH levels measure follicle-stimulating hormone in your blood. There is no single normal result for everyone: interpretation depends on your laboratory, reproductive stage, menstrual cycle timing, medicines and the reason for testing. A high or low result is a clue to investigate, rather than a diagnosis by itself.
If you are looking at a flagged blood test, start with the reference range printed beside your result. Then check when the sample was taken and what question your clinician wanted the test to answer.
This guide provides health education. Discuss individual results and treatment decisions with your healthcare professional.
- Example normal FSH ranges
- FSH levels by age and reproductive stage
- High and low results
- FSH and fertility
- FSH and menopause
- What to do with your result
What Is FSH, and What Does It Do?
Follicle-stimulating hormone, or FSH, is produced by the pituitary gland. It participates in the hormone feedback system connecting the brain with the ovaries or testes.
In people with ovaries, FSH supports the development of ovarian follicles, which contain eggs. In people with testes, it supports sperm production. Its activity also matters during puberty. These functions explain why clinicians may request FSH testing for different reproductive and developmental concerns.
Cleveland Clinic explains FSH function and the hormone feedback system.
What Are Normal FSH Levels?
Normal FSH levels are laboratory-specific. A range for the follicular phase cannot automatically be applied to someone after menopause or to an adult male. Even laboratories testing the same population can publish different intervals.
The table below uses the adult FSH reference intervals published by Gloucestershire Hospitals NHS Foundation Trust. These are examples from one laboratory, not universal diagnostic thresholds.
| Group or cycle phase | FSH, IU/L | Interpretation reminder |
|---|---|---|
| Adult female, follicular phase | 1 to 9 | The phase before ovulation; timing within the phase can matter. |
| Adult female, ovulatory phase | 6 to 26 | A rise around ovulation may be expected. |
| Adult female, luteal phase | 1 to 9 | The phase after ovulation. |
| After menopause | 30 to 118 | A higher range is expected at this reproductive stage. |
| Adult male | 1 to 7 | Interpret alongside symptoms and other relevant tests. |
Use your own report's interval first. A value outside this example table may fall inside your laboratory's range. IU/L and mIU/mL are numerically equivalent units: 1 IU/L equals 1 mIU/mL.
Source: Gloucestershire Hospitals: LH and FSH laboratory reference ranges.
Normal FSH Levels by Age Chart: What Age Can Tell You
An age chart can help organize the discussion, but it cannot assign a reliable personal FSH target from your birthday alone. For someone who menstruates, cycle phase and test purpose remain important at every reproductive age.
| Life stage | What clinicians consider |
|---|---|
| Before or during puberty | Pediatric reference intervals, pubertal development and the reason for testing. |
| Reproductive years with menstrual cycles | Cycle day, the laboratory interval, symptoms and any fertility assessment. |
| Under 40 with irregular or absent periods | Pregnancy and other causes, including premature ovarian insufficiency where appropriate. |
| Ages 40 to 44 with menopause symptoms | Menstrual history and whether testing would help clarify suspected early menopause. |
| Age 45 or older with typical menopause symptoms | Symptoms and menstrual history; routine FSH testing is often unnecessary. |
| After menopause | The laboratory's postmenopausal interval and why the test was requested. |
A menopause reference range is not a rule that everyone of a certain age must meet. Likewise, an age-related fertility concern cannot be resolved by checking whether FSH is inside a chart.
See NICE menopause guidance and ASRM guidance on premature ovarian insufficiency.
What Do High or Low FSH Levels Mean?
High FSH levels
Higher FSH can be expected after menopause. Before menopause, an elevated result may suggest reduced ovarian function, depending on timing and the accompanying hormone results. In males, high FSH can suggest impaired testicular function.
Low FSH levels
Low results can occur when signaling from the hypothalamus or pituitary is reduced. In females, pregnancy, being markedly underweight or recent rapid weight loss may also be relevant. Clinicians interpret the whole pattern rather than treating low FSH as automatically favorable.
Neither pattern identifies its cause on its own. Menstrual changes, fertility difficulties and developmental concerns can arise from several conditions. Symptoms cannot tell you the FSH number.
Source: UCSF's explanation of FSH blood test results.
What Is a Normal FSH Level to Get Pregnant?
There is no FSH number that guarantees pregnancy or rules it out. Ovarian reserve tests help assess aspects of the available follicle pool and expected response to fertility treatment. They are not a complete measurement of natural conception chances.
For a baseline ovarian reserve assessment, FSH is commonly measured on menstrual cycle day 2, 3 or 4 with estradiol. FSH varies within and between cycles, and elevated estradiol can suppress FSH, making an apparently normal result misleading.
A clinician may use anti-Müllerian hormone, or AMH, and an ultrasound antral follicle count for additional information. These tests do not directly grade egg quality. A normal FSH result also does not exclude diminished ovarian reserve.
Source: ASRM committee opinion on ovarian reserve testing.
How do FSH and LH levels fit together?
Luteinizing hormone, or LH, works with FSH in reproductive hormone regulation. Clinicians may assess these results alongside estradiol, testosterone or other tests. An isolated FSH-to-LH ratio is not a substitute for assessing symptoms, history and the relevant diagnostic criteria.
MedlinePlus describes why FSH is often tested with other hormones.
What FSH Level Indicates Menopause?
FSH generally rises as ovarian activity declines, but a single number does not establish menopause in every situation. In otherwise healthy people aged 45 or older with typical symptoms, NICE recommends identifying perimenopause or menopause from clinical history without routine laboratory testing. Menopause is generally identified after 12 months without a period when hormonal contraception is not being used.
NICE advises against using FSH to identify menopause in people taking combined estrogen-progestogen contraception or high-dose progestogen. Tell your clinician about hormonal medicines; do not stop them on your own to obtain a test.
What about high FSH before age 40?
Premature ovarian insufficiency, or POI, needs a clinical assessment. The ASRM-hosted guideline uses irregular or absent cycles for at least four months together with FSH above 25 IU/L as diagnostic criteria. Repeat FSH after four to six weeks is advised when there is diagnostic uncertainty. Pregnancy and medication effects must also be considered.
This POI threshold is not a universal menopause cutoff or a diagnosis to apply from a home test.
Sources: NICE menopause recommendations and ASRM-hosted POI guideline.
How Is an FSH Blood Test Done?
A healthcare professional takes a blood sample, usually from a vein in your arm. Brief discomfort or bruising can occur. If you menstruate, ask which cycle day is appropriate for the purpose of your test.
Follow the laboratory's preparation instructions and tell the ordering clinician about prescriptions, hormonal treatment and supplements. Ask whether fasting is needed if other blood tests are being collected at the same appointment.
Source: MedlinePlus FSH test information.
What Should You Do With Your FSH Result?
- Keep the full report. Record the number, units and laboratory reference interval.
- Record the context. Note cycle day, menstrual changes, symptoms and hormone medicines.
- Clarify the test purpose. Fertility assessment and investigation of menopause or pituitary concerns use different clinical reasoning.
- Ask about related findings. Find out whether other hormones, imaging or repeat testing would change the interpretation.
- Agree on a next step. Ask what action is appropriate and when follow-up should occur.
Useful questions include: “Was this tested at the right time?”, “Does this flag matter in my situation?” and “What can this test not tell us?”
When should you seek an assessment?
Arrange medical advice for persistent irregular or absent periods, unexpected menopause symptoms before 45, or concerns about sperm production or pubertal development.
For people trying to conceive through regular unprotected intercourse, ASRM recommends fertility evaluation after 12 months when the female partner is under 35, or after six months at 35 or older. More immediate assessment may be appropriate over 40, or sooner when there are known concerns such as irregular cycles. Evaluation may involve both partners, rather than FSH alone.
Source: ASRM guidance on fertility evaluation.
Frequently Asked Questions About FSH Levels
Is FSH of 10 normal?
It depends on the units, laboratory interval, cycle phase and clinical context. A result of 10 should not automatically be labeled normal, infertile or menopausal without that information.
Can FSH levels change from month to month?
Yes. Baseline FSH can vary between menstrual cycles. Ask whether repeating the test would help answer the clinical question.
Does high FSH mean pregnancy is impossible?
No. FSH alone cannot determine whether conception is possible. Discuss the result alongside age, reproductive history and the rest of the fertility evaluation.
Should everyone over 45 test FSH for menopause?
No. Typical menopause symptoms and menstrual history often provide the information needed without routine FSH testing.
Should I try to lower FSH with supplements?
Ask what is causing the result before choosing a treatment. Lowering a laboratory number is not the same as improving ovarian function. For POI specifically, the ASRM-hosted guideline states that no intervention has reliably been shown to increase ovarian activity and natural conception rates.
Are IU/L and mIU/mL different FSH values?
They are numerically equivalent units. A result of 8 IU/L equals 8 mIU/mL; the laboratory's method and reference interval still matter.