Fertility Blood Test UK: AMH, FSH and What They Mean

Medically reviewed content. Last updated: February 2026.

Around 1 in 7 couples in the UK experience difficulty conceiving, affecting an estimated 3.5 million people. If you have been trying for a baby without success, or simply want to understand your reproductive health before you start, a fertility blood test can provide answers that months of uncertainty cannot.

Blood tests can reveal hormonal imbalances, ovarian reserve status, thyroid dysfunction, and nutritional deficiencies — all of which are treatable conditions that may be standing between you and a successful pregnancy. Rather than waiting 12 months before your GP will refer you (the standard NHS criterion under NICE guideline CG156), private fertility blood testing lets you get a detailed hormonal picture on your own timeline, without a referral.

This guide explains every key fertility marker, when to test, what the results mean, and how NHS and private testing compare in the UK.

The Key Fertility Blood Markers

A comprehensive fertility blood test measures several hormones that work together to regulate your menstrual cycle, egg development, and ovulation. Understanding what each marker does — and what abnormal levels mean — is the first step toward taking control of your fertility journey.

AMH (Anti-Müllerian Hormone) — Ovarian Reserve

AMH is produced by the small follicles in your ovaries and is the most reliable blood marker of your ovarian reserve — the number of eggs you have remaining. Unlike FSH and LH, AMH remains relatively stable throughout your menstrual cycle, so it can be tested on any day.

AMH is not routinely included in standard NHS blood tests. You will usually only have AMH tested on the NHS once you have been referred to a fertility specialist, which can take months. Private testing gives you access to this critical marker immediately.

It is important to understand that AMH tells you about egg quantity, not egg quality. A low AMH does not mean you cannot conceive naturally — it means your window may be narrowing and time is a factor.

FSH (Follicle-Stimulating Hormone)

FSH stimulates the growth of ovarian follicles each month. It must be tested on cycle day 2–5 for the reading to be clinically meaningful. Your brain produces more FSH when your ovaries need extra stimulation, so elevated FSH (above 10 IU/L) on day 3 can signal diminished ovarian reserve — your body is working harder to recruit follicles because fewer are available.

An ideal day 3 FSH level is below 8 IU/L. Levels above 15 IU/L suggest significantly reduced ovarian reserve and may affect the success of fertility treatments such as IVF.

LH (Luteinising Hormone)

LH triggers ovulation. On day 3 of your cycle, LH and FSH should be roughly equal (both around 3–8 IU/L). An LH:FSH ratio of 2:1 or higher — for example, LH of 15 IU/L with FSH of 5 IU/L — is a hallmark finding in women with polycystic ovary syndrome (PCOS). While the LH:FSH ratio alone is no longer used to diagnose PCOS (the Rotterdam criteria require two out of three features: oligo-anovulation, hyperandrogenism, or polycystic ovarian morphology on ultrasound), it remains a valuable piece of the clinical picture.

Oestradiol (E2)

Oestradiol is the primary form of oestrogen in reproductive-age women. A baseline oestradiol test on cycle day 2–5 should typically read between 80–200 pmol/L. Elevated baseline oestradiol (above 250 pmol/L) can artificially suppress FSH, making your FSH appear normal when it is not — which is why FSH and oestradiol should always be interpreted together.

Progesterone — The Ovulation Confirmation Test

Progesterone rises sharply after ovulation and is tested 7 days before your expected period (often called a “day 21 test” for a 28-day cycle). A level of 30 nmol/L or above confirms that ovulation occurred. Between 16–30 nmol/L is borderline — you may have ovulated but tested slightly too early. Below 16 nmol/L suggests you did not ovulate that cycle.

If your cycle is longer or shorter than 28 days, adjust your testing day accordingly. For a 35-day cycle, test on day 28. For a 25-day cycle, test on day 18.

AMH: The Ovarian Reserve Test in Detail

AMH deserves its own section because it is arguably the most important single fertility marker, yet it is also the most misunderstood.

How AMH Works

Your ovaries contain a finite number of eggs from birth. Each month, a group of small (antral) follicles begin to develop, and the granulosa cells surrounding these follicles produce AMH. The more antral follicles you have, the higher your AMH level. As your egg supply naturally diminishes with age, AMH levels gradually decline.

AMH Reference Ranges by Age

AMH levels vary significantly between individuals of the same age, but the following median values and ranges (based on large population studies using the Beckman Coulter Access assay, measured in pmol/L) give a useful guide:

Note: Some labs report AMH in ng/mL. To convert, divide pmol/L by 7.14 (e.g., 14 pmol/L ≈ 2.0 ng/mL). Always check which unit your lab uses.

What Low AMH Means

An AMH below approximately 5.4 pmol/L (0.75 ng/mL) is generally considered low for women under 40 and may indicate diminished ovarian reserve (DOR). This does not mean you cannot conceive — women with low AMH can and do get pregnant naturally — but it does suggest:

• You may have fewer eggs remaining than average for your age
• The window for conception may be shorter
• If IVF is needed, fewer eggs may be retrieved per cycle
• You may want to consider egg freezing sooner rather than later if children are in your future plans

What High AMH Means

An AMH above 35 pmol/L (approximately 5 ng/mL) may indicate a high antral follicle count, which is often associated with PCOS. Women with PCOS typically have many small follicles that produce AMH but do not mature and ovulate normally. High AMH in this context can actually signal ovulatory dysfunction rather than superior fertility.

What AMH Does Not Tell You

AMH reflects the quantity of remaining eggs but says nothing about egg quality. Egg quality is primarily determined by age. A 38-year-old with an AMH of 25 pmol/L has plenty of eggs in terms of number, but the chromosomal quality of those eggs is still that of a 38-year-old. Conversely, a 28-year-old with a low AMH of 5 pmol/L has fewer eggs but they are likely to be of good chromosomal quality.

When to Test: Cycle Day Matters

Timing is critical for fertility blood tests. Testing on the wrong day of your cycle can produce misleading results that lead to unnecessary worry or false reassurance. The table below summarises optimal testing windows:

Practical tip: If your cycle is regular, book your blood draw for the morning of day 3. This lets you capture FSH, LH, oestradiol, and AMH in a single appointment. Then schedule a second draw 7 days before your expected period for progesterone.

Male Fertility Markers: The Overlooked Half

Male factor contributes to 30–50% of all fertility problems, yet it is routinely under-investigated. Many couples spend months focused exclusively on the woman’s hormones before anyone thinks to test the male partner.

While semen analysis is the cornerstone of male fertility testing, blood tests provide important additional information:

Testosterone

Testosterone is essential for sperm production (spermatogenesis). Low testosterone can reduce sperm count and quality. Total testosterone should ideally be tested first thing in the morning, when levels peak. The normal range is approximately 8.6–29 nmol/L, but for optimal fertility, levels in the upper half of this range are preferred.

SHBG (Sex Hormone Binding Globulin)

SHBG binds to testosterone in the bloodstream. Around 98% of testosterone is protein-bound, with one-third tightly bound to SHBG and unavailable to cells. Research shows that about 20% of men with a normal total testosterone actually have low free or bioavailable testosterone because their SHBG is elevated. Without measuring SHBG, you cannot calculate free testosterone — and it is free testosterone that the body actually uses.

FSH and LH in Men

FSH stimulates the Sertoli cells in the testes to support sperm development. Elevated FSH in men often indicates that the testes are not producing sperm efficiently. LH stimulates the Leydig cells to produce testosterone. Together, FSH, LH, and testosterone paint a clear picture of the hormonal axis driving male fertility.

If you are investigating fertility as a couple, ensure that both partners are tested from the outset. A comprehensive male hormone panel alongside semen analysis can save months of misdirected effort.

Thyroid and Fertility: A Critical Connection

The thyroid gland regulates your metabolism, but its influence extends far into reproductive health. Even mildly underactive thyroid function (subclinical hypothyroidism) can impair fertility and increase the risk of miscarriage.

Why TSH Matters for Conception

TSH (thyroid-stimulating hormone) is the primary screening marker. While the general population reference range extends up to 4.0–4.5 mIU/L, the British Thyroid Association recommends a TSH target of 0.2–2.5 mIU/L for women planning pregnancy. The American Society for Reproductive Medicine (ASRM) 2024 guideline similarly acknowledges that TSH levels above 4.0 mIU/L are associated with miscarriage risk.

If your TSH is between 2.5 and 4.5 mIU/L and you are struggling to conceive, it is worth discussing with your GP whether a trial of low-dose levothyroxine might be appropriate. NICE recommends referral to an endocrinologist for any woman with overt or subclinical hypothyroidism who is planning pregnancy or is already pregnant.

Beyond TSH

A complete thyroid picture includes Free T4 (thyroxine) and thyroid antibodies (anti-TPO and anti-thyroglobulin). Thyroid antibodies are present in approximately 5–10% of women of reproductive age and are associated with increased miscarriage risk, even when TSH is within the normal range. For a full guide, read our article on thyroid blood tests in the UK.

Nutritional Markers for Fertility

Hormones get most of the attention, but nutritional deficiencies can quietly sabotage conception and early pregnancy. The following markers are often included in comprehensive fertility panels and are well worth checking:

Folate

Folate (vitamin B9) is essential for DNA synthesis and cell division — processes at the very heart of conception and early embryo development. The UK Scientific Advisory Committee on Nutrition (SACN) recommends that all women who could become pregnant take 400 micrograms of folic acid daily, starting at least 2–3 months before conception and continuing through the first 12 weeks of pregnancy. This is to prevent neural tube defects such as spina bifida.

From late 2026, UK non-wholemeal wheat flour will be mandatorily fortified with folic acid, but supplementation remains recommended as dietary intake alone is often insufficient.

Vitamin D

Vitamin D deficiency is endemic in the UK, particularly between October and March. Research has linked vitamin D deficiency to reduced fertility, poorer IVF outcomes, and pregnancy complications including pre-eclampsia and gestational diabetes. The NHS recommends a daily supplement of 10 micrograms (400 IU) of vitamin D year-round, with many fertility specialists suggesting higher doses if your blood levels are below 50 nmol/L.

Ferritin (Iron Stores)

Ferritin measures your body’s iron reserves. Low ferritin is common in women of reproductive age due to menstrual blood loss and can cause fatigue, poor egg quality, and anovulation. While a ferritin level above 15 µg/L is technically “normal,” many fertility specialists prefer to see levels above 30 µg/L, and ideally above 50 µg/L, before conception.

Vitamin B12

B12 is a co-factor in DNA synthesis and works alongside folate. Deficiency is particularly common in vegetarians, vegans, and those taking metformin (often prescribed for PCOS). Low B12 has been associated with recurrent miscarriage and ovulatory infertility. A serum B12 above 300 ng/L is generally considered optimal for conception.

HbA1c (Blood Sugar Control)

HbA1c reflects your average blood sugar over the preceding 2–3 months. Insulin resistance is a core feature of PCOS, and elevated blood sugar impairs ovulation, egg quality, and implantation. An HbA1c below 42 mmol/mol (6.0%) is desirable for women trying to conceive. Even modest blood sugar improvements through diet and exercise can restore ovulation in women with PCOS-related anovulation.

NHS Fertility Testing vs Private Testing in the UK

Understanding the differences between NHS and private fertility testing can save you time and frustration.

NHS Fertility Testing Pathway

Under NICE guideline CG156, your GP should refer you for specialist fertility investigation if:

• You have been trying to conceive for 12 months or more without success
• You are aged 36 or over and have been trying for 6 months
• There is a known condition that may affect fertility (e.g., previous chemotherapy, absent periods, endometriosis)

Once referred, the NHS will typically provide:

• Blood tests: FSH, LH, progesterone (day 21), TSH, prolactin, and rubella immunity
• Semen analysis for the male partner
• Pelvic ultrasound and potentially a tubal patency test (HSG or HyCoSy)
• AMH may be offered at the specialist level, but not always at the GP level

Waiting times vary significantly by region. Many NHS trusts work to an 18-week referral-to-treatment pathway, but in high-demand areas, waits of 6 months to over a year are not uncommon. Research from 2025 indicates typical waiting times of 6 weeks to 4 months for initial specialist appointments, with some areas reporting waits of up to 3 years.

What Private Fertility Blood Testing Offers

Private testing removes the waiting and provides a broader panel. A comprehensive private fertility panel such as the Female Hormones Clarity 31 typically includes all of the above markers plus AMH, testosterone, SHBG, free T4, vitamin D, ferritin, folate, B12, HbA1c, and full blood count — giving you a significantly more complete picture.

Private testing does not replace NHS care — it complements it. Many women use private results to have more informed conversations with their GP, fast-track referrals where appropriate, and identify treatable issues (like vitamin D deficiency or subclinical hypothyroidism) while they wait for NHS appointments.

For the most comprehensive hormonal picture, the Peak Insights 70 blood test covers 70 biomarkers including all fertility hormones, full thyroid panel, metabolic health markers, and a complete nutritional profile.

Frequently Asked Questions

What is the best fertility blood test in the UK?

The best fertility blood test covers a comprehensive panel including AMH, FSH, LH, oestradiol, progesterone, testosterone, SHBG, thyroid function (TSH and Free T4), and key nutritional markers such as vitamin D, folate, ferritin, and B12. A minimum of 20–30 biomarkers gives you a thorough picture. At-home tests with a professional phlebotomist visit, such as the Female Hormones Clarity 31, combine convenience with laboratory accuracy.

Can I get a fertility blood test on the NHS?

Yes, but with limitations. Your GP will usually only refer you for fertility investigations after 12 months of trying to conceive (or 6 months if you are 36 or older), unless there is a known medical reason. NHS initial tests typically cover FSH, LH, progesterone, and TSH. AMH is usually only available once you reach the specialist stage. Private testing provides immediate access to all markers without a referral or waiting period.

What is a good AMH level for my age?

AMH varies widely between individuals. As a general guide, median AMH is approximately 26.6 pmol/L for women aged 20–25, declining to around 13.7 pmol/L by age 36–40. An AMH below 5.4 pmol/L is generally considered low. However, AMH should always be interpreted alongside age and other fertility markers — not in isolation. A low AMH does not mean you cannot conceive; it suggests your time frame may be shorter.

When in my cycle should I have fertility blood tests?

FSH, LH, and oestradiol should be tested on cycle day 2–5 (where day 1 is the first day of full menstrual bleeding). Progesterone should be tested 7 days before your expected period — day 21 for a 28-day cycle, day 28 for a 35-day cycle. AMH, testosterone, SHBG, thyroid hormones, and nutritional markers can be tested on any day of your cycle.

What does a high LH:FSH ratio mean for fertility?

An LH:FSH ratio of 2:1 or higher (measured on cycle day 2–5) is commonly seen in women with polycystic ovary syndrome (PCOS). Elevated LH stimulates excess androgen (testosterone) production in the ovaries, which can prevent follicles from maturing and ovulating. If you have an elevated ratio alongside irregular periods or signs of excess androgens (acne, excess hair growth), speak to your GP about a PCOS assessment.

Does a low AMH mean I cannot get pregnant?

No. AMH reflects the quantity of eggs remaining, not their quality. Women with low AMH can and do conceive naturally. However, a low AMH suggests that your ovarian reserve is diminishing faster than average for your age, which means the window for natural conception may be shorter. It also means that if IVF is required, fewer eggs may be retrieved per cycle. If your AMH is low, earlier rather than later action — whether that is focused trying, fertility treatment, or egg freezing — is generally advised.

Should my partner have a fertility blood test too?

Absolutely. Male factor infertility accounts for 30–50% of all fertility problems, yet it is frequently overlooked. A male hormone panel measuring testosterone, SHBG, FSH, and LH, alongside a semen analysis, can identify hormonal issues that may be affecting sperm production or quality. Testing both partners simultaneously saves time and ensures no treatable cause is missed.

How much does a private fertility blood test cost in the UK?

Private fertility blood tests in the UK typically range from £100 for a basic hormone panel (FSH, LH, AMH) to £150–£300 for a comprehensive panel covering 30+ markers including hormones, thyroid function, and nutritional markers. Many providers include a professional phlebotomist home visit in the price. Given that fertility clinic consultations can cost £250–£500 before any tests are run, an at-home blood test is often the most cost-effective first step.

Taking the Next Step

If you are trying to conceive, planning to start a family in the coming years, or simply want to understand your reproductive health, a fertility blood test is one of the most practical steps you can take. The markers discussed in this guide — from AMH and FSH to thyroid function and vitamin D — are all modifiable or actionable. Low vitamin D can be supplemented. Subclinical hypothyroidism can be treated. PCOS-related anovulation can often be managed. And understanding your ovarian reserve gives you the information you need to make decisions about timing.

The key is not to wait. Every month of unexplained difficulty is a month that could have been spent addressing a treatable cause. Whether you test privately or through the NHS, getting your fertility markers checked is the evidence-based starting point.

This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for guidance on your individual circumstances. If you have been trying to conceive for 12 months (or 6 months if you are 36 or older), contact your GP for a referral. For information on menopause blood testing, see our dedicated guide.