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  • Writer's pictureDr Katie Psarou

Fertility Blood Tests: A Comprehensive Guide to Understanding Your Reproductive Health

Updated: Feb 22

Are you planning to grow your family and struggling to conceive?

Discover the key blood tests to assess and understand your fertility better.

Fertility blood tests samples

Understanding your reproductive health is the first step for couples looking to enhance their fertility. By gaining insights into your current nutritional and hormonal status, you can proactively tackle any underlying issues.

In this article you will find a comprehensive array of fertility blood tests available for both men and women.

If you've already received your fertility blood test results, this guide will help you make sense of them, whether there are areas of concern, and equip you with strategies to optimise your fertility.

Let's explore these tests and what they can reveal.

1. What Fertility Tests You Need on Your TTC Journey?

One in six couples will experience infertility. As infertility can affect either one or both partners, it is best to visit your doctor as a couple for some further tests.

This is important if you have been trying to conceive (TTC) for longer than 1 year of unprotected intercourse or over 6 months if you are aged over 35.

There are many factors that can affect fertility including:

  • Egg and sperm quality

  • Body weight

  • Hormone imbalance

  • Lifestyle and environment for example smoking and drug use

  • Medical conditions or illness and medications

When you see your doctor you may be offered all or some of these fertility tests. These fertility tests include:

  • Antibodies for Chlamydia (via swab or urine sample) for both partners, as this sexually transmitted infection can have an impact on fertility. This can be treated with antibiotics.

  • Antibodies for Rubella/ German Measles to ensure you are immune before a woman becomes pregnant

  • Ultrasound scan to count the number of follicles in the ovaries for women

  • Ultrasound scan or X-ray or laparoscopy to check the fallopian tubes in women for any damage due to endometriosis, fibroids, blockage.

  • Ultrasound scan to check for varicocele and hydrocele for men both of which can affect the sperm quality

  • Semen analysis for men which provides more detail about the sperm quality

  • Blood tests as outlined in sections below

2. Fertility Blood Tests: Your Window to Reproductive Health

Fertility blood tests are a crucial tool in assessing your ability to conceive. They offer valuable information for both men and women, helping to identify any underlying issues that might affect your chances of having a healthy pregnancy.

Tests include nutritional bloods, hormones and other biomarkers that need to be done in combination (not in isolation) for a better interpretation of what is going on in your body.

It's important to remember that these tests are not just for those undergoing fertility treatment; many couples find value in understanding their reproductive health before embarking on their TTC journey.

Keep in mind that the values for these tests may vary between different labs, so always consult with your healthcare provider for a personalised interpretation of your results. Sometimes the blood results show that everything is “normal” or in “acceptable” levels or there is “no further action”. Yet, some blood tests require specific values when TTC compared to a normal range values.

You may find your TTC journey is filled with uncertainties, but with knowledge, support, and the right guidance, you can decide the next steps on your TTC journey.

These blood tests are often available on the NHS, but you can also do these privately, which is often super quick and easy.

The table below shows when to do these fertility blood tests and whether they need fasting blood samples. For further information about the individual tests, see the sections below.

table shoing fertility blood tests timing and whether to fast

3. Nutritional Bloods for Men and Women: Fueling Your Fertility

Did you know that your nutritional status can impact your fertility? Deficiencies in vitamins and minerals may hinder your ability to conceive. Let's examine the nutritional blood tests that can shed light on your dietary needs:

Fertility nutrients in virant coloured fruit

3.1 Vitamin D

Vitamin D plays a role in fertility for both men and women. If you've been trying to conceive without success, consider checking your Vitamin D levels.

Research demonstrates that rectifying a deficiency in vitamin D through appropriate supplements can enhance sperm function and quality, ovarian function, and increase your chances of conception during fertility treatment.

Vitamin D is a fat-soluble vitamin obtained from sunlight and certain foods like oily fish and eggs. Supplementation may be necessary if you:

  • live in a region with limited sunlight, particularly the winter months

  • Have darker skin which reduces the ability of the skin to produce this vitamin

  • Have a high BMI (above 30) which prevents the circulation of this vitamin around your body

  • Have certain medical conditions (e.g., coeliac disease, inflammatory bowel disorders, cystic fibrosis) or

  • Have undergone weight loss surgery

Your required dose depends on your blood level, ideally set at 75nmol/L (30ng/mL). Consult a fertility dietitian for personalised guidance.

3.2 Vitamin B12

Vitamin B12 plays a crucial role in fertility. For men, it promotes healthy sperm by boosting count, movement, and reducing sperm DNA damage. In women, it supports egg development.

Deficiency is associated with conditions like megaloblastic anemia and pernicious anemia, linked to reduced fertility and miscarriage.

This water-soluble vitamin is essential for DNA synthesis and keeps your blood and nerve cells healthy. It's abundant in animal products like meat, fish, eggs, and dairy.

Your B12 levels might be low if you:

  • Follow a vegan or plant-based diet with limited animal foods

  • Have pernicious anemia or a thyroid condition

  • Suffer from conditions hindering gut absorption (e.g., coeliac disease, inflammatory bowel disorders)

  • Underwent weight loss surgery that bypasses B12 absorption

  • Use long-term medications like metformin or gastric acid inhibitors.

Correcting B12 levels may involve dietary adjustments or supplements. Consult your doctor or fertility dietitian for personalised guidance.

3.3 Folate

Taking folic acid, the synthetic form of folate, along with folate-rich foods is crucial for preventing neural tube defects (NTD).

Research confirms that folic acid reduces infertility risks associated with ovulation disorders like Polycystic Ovarian Syndrome (PCOS) by enhancing progesterone levels during the menstrual cycle's luteal phase.

Additionally, adequate folate levels in the blood and diet increase IVF success rates, while men with high folate levels experience fewer sperm abnormalities (sperm DNA fragmentation and chromosomes).

Folate, a water-soluble vitamin found in green leafy veggies, citrus fruits, nuts, and seeds, is vital for DNA synthesis and cell division, making it essential for reproductive health.

Low folate levels may result from:

  • Medical conditions hindering gut absorption (e.g., coeliac disease, inflammatory bowel disorders)

  • MTHFR genetic polymorphism, reducing the body's ability to convert folate

  • Weight loss surgery bypassing folate absorption

  • Inadequate dietary folate intake, even with folic acid supplements

  • Moderate to high alcohol consumption (e.g., over 2 bottles of wine weekly)

Consider higher folic acid supplementation when trying to conceive if:

  • Blood levels are below healthy range

  • BMI exceeds 30kg/m2

  • You have diabetes, coeliac disease, sickle-cell anemia, or thalassemia

  • A history of NTD or family history exists

  • You take medications affecting folate absorption, such as antiepileptic drugs.

3.4 Iron

Sufficient iron levels are crucial for fertility, benefiting egg maturation, sperm quality, and reducing miscarriage risk. Symptoms of low iron intake include fatigue, breathlessness, and weakness.

To check your iron levels, several blood tests are available, including a full blood count (FBC), serum iron levels, and ferritin levels. FBC provides a result for heamoglobin level (a blood protein), assessing its ability to transport oxygen throughout the body. Serum iron levels gauge circulating iron, while ferritin levels show total iron stores.

Performing these tests together is recommended, as high ferritin levels can result from inflammation, masking iron deficiency anemia.

Iron, essential for physical growth, nerve development, cell function, and hormone production, exists in two main forms: haem and non-haem. Rich iron sources include lean meat, seafood, legumes, nuts, vegetables, and fortified cereals.

Low iron levels may stem from:

  • Heavy menstrual bleeding

  • Medical conditions or surgeries hindering iron absorption or causing blood loss (e.g., coeliac disease, inflammatory bowel disorders, weight loss surgery)

If supplementation is necessary to correct iron stores, consult your doctor or fertility dietitian for appropriate dosing.

Want to have all this valuable information at your fingertips? Download this FREE PDF guide, your ultimate resource for understanding fertility blood tests and optimising your reproductive health. Don't wait—take control of your fertility journey today!

4. Hormonal Balance: The Key to Fertility

Your hormonal balance plays a pivotal role in your reproductive health. Understanding these hormones and their functions is essential. Here's a closer look at some of the hormones assessed in fertility blood tests.

Hormone balance tests for egg and sperm health

4.1 Fertility Hormone Blood Tests for Women

In this section we are going through the most common tests to check for female fertility. You will learn about which hormones are responsible for fertility, what their role is in your body, what the results can tell you about your reproductive health and when to test.

So if your Doctor has requested bloods, you will know exactly which day in your cycle to have them done and what to expect from the results.

4.1.1 FSH - Follicle Stimulating Hormone

Follicle stimulating hormone is released by the pituitary gland in the brain during the menstrual cycle's initial phase (follicular phase). FSH plays a crucial role in preparing ovarian follicles to grow, which house eggs. One egg is going to mature ready to be released during ovulation.

FSH levels fluctuate throughout the menstrual cycle, but will rise and fall before ovulation. Cycle day 1 is the first day of your period, so typically, the test is performed on cycle days 2-5. You can test up to day 8 if your cycles are irregular. If your cycles are absent, the test can be conducted at any time.

This test assesses ovarian function, ovulation, and predicts your response to fertility drugs for IVF. Elevated FSH levels point to ovulatory issues like PCOS or primary ovarian insufficiency (POI), while low levels suggest reduced chances of ovulation that month. Please note this test alone does not confirm ovulation.

4.1.2 Luteinizing Hormone - LH

Produced by the pituitary gland, LH's levels surge just before ovulation, triggering egg maturation and release. It also prompts the ovaries to produce progesterone and estrogen for pregnancy preparation.

This test, like FSH, is conducted at the start of the menstrual cycle (cycle days 2-5). It detects hormonal imbalances and ovulatory disorders, such as PCOS or early menopause, particularly if you have irregular periods.

Testing around mid-cycle helps predict ovulation timing. Low levels may indicate anovulation, potentially prolonging conception, while high levels could point to premature menopause. This test can point as an indicator of ovulation but it does not confirm ovulation.

4.1.3 Oestradiol (Oestrogen)

Oestrogen (E2) surges in the follicular phase of a woman’s cycle, preparing ovaries for egg growth and ovulation, then drops as FSH and LH take over. It rises again during the luteal phase, shortly after ovulation.

If you don't get pregnant, oestrogen levels will fall and menstruation will start.

Tested on the same day as FSH and LH, oestrogen levels can signal hormonal imbalances, if you are experiencing abnormal or missing menstrual cycles or abnormal bleeding in your cycle.

Keep in mind that oestrogen fluctuates throughout your cycle, so interpretations should consider the cycle phase and trends over time.

4.1.4 Progesterone

Produced by the ovaries during ovulation, progesterone rises during the luteal phase, preparing your body for pregnancy by thickening the uterine lining to support implantation of the fertilised egg.

This test confirms ovulation. High levels indicate ovulation, while low progesterone levels suggest anovulation or a luteal phase defect (short luteal phase, less than 10 days from ovulation).

Unlike FSH, LH, and Oestrogen, progesterone is tested during the luteal phase, usually 7 days post-ovulation or 7 days before your period is due. If you test on the day of your ovulation or earlier than 7 days after ovulation, then it is too early to show high levels of progesterone. So it would be too early to show ovulation in your test results.

For regular 28-day cycles, test on day 21; if cycles are 35 days, test on day 28. Irregular cycles can align with your period's arrival or be tracked using Basal Body Temperature (BBT) or ovulation prediction kits (OPKs). These kits show when ovulation is near, allowing you to take the progesterone blood test 7 days after.

Progesterone levels should be 30nmol/L and above to confirm ovulation. Consistently low levels may need progesterone supplementation under a doctor's guidance to support pregnancy.

4.1.5 AMH - Anti-Mullerian Hormone (Ovarian Reserve)

AMH, secreted by antral follicles in the ovaries, reflects ovarian reserve (the number of eggs in the ovaries). High levels suggest a good reserve, while low levels show the opposite.

As you age this hormone reduces and stops being produced when you reach menopause. Higher body weight can also lower AMH levels.

A lower result doesn't mean all hope is lost; you can still enhance the quality of remaining eggs.

This test also predicts ovarian responsiveness and the potential for obtaining enough eggs during fertility treatment.

4.1.6 Prolactin

Prolactin, produced by the pituitary gland, plays a role in milk production and breast development. It's naturally elevated during pregnancy and breastfeeding, which can suppress FSH and LH, leading to missed periods.

If you are breastfeeding, the stimulation of the nipple is sufficient enough to keep sending signals to the brain to keep the prolactin levels high.

Outside pregnancy and breastfeeding, high prolactin levels may signify ovulatory issues, a shortened luteal phase, or irregular cycles. It's often performed if irregular periods or ovulation problems are a concern.

High levels may indicate a condition affecting fertility, such as hyperprolactinemia. This condition can be treated with medication.

Further evaluation is often necessary to determine the underlying cause and appropriate treatment. Checking prolactin along with Thyroid Stimulating Hormone helps rule out hypothyroidism.

High prolactin can also result from stress, exercise, sexual activity, or certain medications (antidepressants, anti-sickness or blood pressure).

4.1.7 Testosterone

Women naturally produce testosterone, a hormone often associated with males. It's produced in the ovaries and adrenal cortex glands, vital for ovarian function.

High testosterone levels help diagnose ovulatory disorders, like PCOS, if accompanied by irregular periods, excess facial or body hair, and weight gain.

4.1.8 DHEAs - Dehydroepiandrosterone- Sulfate

DHEAs, produced by the adrenal glands, ovaries, and testes, play a role in oestrogen and testosterone production.

Normal to slightly elevated levels may occur with irregular periods, often seen in PCOS. This test is beneficial if you have symptoms like acne, excess facial or body hair, and irregular periods.

DHEAs levels remain relatively stable throughout the day, but it is best to take this test 1 week before or after your period.

4.1.9 TSH- Thyroid Stimulating Hormone

TSH, released by the brain's pituitary gland, regulates thyroid hormones (T4 and T3) from the thyroid gland.

High TSH suggests an underactive thyroid (hypothyroidism), while low TSH indicates an overactive thyroid (hyperthyroidism). Both conditions affect fertility in both men and women and may be linked to autoimmune conditions.

Elevated TSH levels over 2.5 mIU/L in women are associated with pregnancy loss, even if the test result shows it’s within the normal range.

Thyroid levels can't be altered by diet or supplements; a fertility specialist or endocrinologist prescribes Thyroxine tablets.

Infertility is common in women with Hashimoto's thyroiditis and Graves' disease. Hyperthyroidism and hypothyroidism can lead to irregular cycles. Stress, illness, and lack of sleep can affect TSH levels, as can Biotin supplements (stop supplements for at least 3 days before taking the test).

TSH is often tested with T4 (thyroxine) and less with T3 (Triiodothyronine) for a comprehensive thyroid function assessment.

Monitoring and treatment of thyroid conditions are crucial for fertility, if you are experiencing fatigue, weight gain or low mood. Vitamin B12 levels should also be checked, as levels can become low or insufficient over time.

4.1.10 SHBG - Sex Hormone Binding Globulin and Free Androgen Index

SHBG, a liver-produced protein, binds with sex hormones like testosterone and oestradiol in the blood and controls testosterone transport. Excessive testosterone can disrupt women's cycles and ovarian function.

SHBG levels are affected by conditions such as liver disease, thyroid issues, or higher body weight. Low SHBG is common in women with PCOS, leading to facial and body hair.

It's tested alongside testosterone to determine the Free Androgen Index. This shows the ratio of total testosterone to SHBG and indicates hormone imbalances.

Want to have all this valuable information at your fingertips? Download this FREE PDF guide, your ultimate resource for understanding fertility blood tests and optimising your reproductive health. Don't wait—take control of your fertility journey today!

4.2 Fertility Hormone Blood Tests for Men

In this section we are going through the most common tests to check for male fertility. You will learn about which hormones are responsible for fertility, what their role is in your body, what the results can tell you about your reproductive health and when to test.

Many of these hormone tests need to be done in combination to better understand your next steps.

4.2.1 FSH - Follicle Stimulating Hormone

FSH is vital for sperm production and transport. It's tested to detect potential sperm issues. Low blood levels of FSH may indicate a lower sperm count due to a blockage or the testicles struggling to produce enough sperm. This test is most effective in the morning (between 8-10 am) when hormone levels peak and gradually decrease over the day.

4.2.2 LH - Luteinizing Hormone

LH stimulates testosterone production in men, crucial for sperm production. High levels may signal hypogonadism, caused by testicular or brain issues. Low levels hinder sperm production, leading to male infertility.

If you have symptoms like low libido, erectile dysfunction, muscle loss, or mood swings, consider testing. Optimal testing time is the morning (between 8-10 am), aligning with hormone secretion peaks during the early hours.

4.2.3 Prolactin

Prolactin, produced by the pituitary gland, is found in small amounts in men. High prolactin can reduce libido, causing headaches and impacting sperm production. This hormone is tested with testosterone in the early morning.

4.2.4 Testosterone

Testes produce testosterone in response to the brain's pituitary gland signal. This hormone is tested to pinpoint infertility causes.

Low levels can result from trauma or injury in the testes, brain-related factors (an autoimmune condition), or infections. It can lead to low libido, erectile dysfunction, reduced sperm production, increased body fat, and weight gain.

High levels are linked to low sperm count, often observed in men aiming to build muscle mass for athletic performance.

4.2.5 SHBG - Sex Hormone Binding Globulin

Produced by the liver, SHBG binds with sex hormones like testosterone and oestradiol in the blood, regulating testosterone transport. In men, it's used to detect hormone imbalances associated with low testosterone, causing low sex drive and erectile dysfunction.

Age, thyroid or liver dysfunction, and obesity impact SHBG levels. It's often conducted in conjunction with other hormone tests like prolactin, FSH, and LH to provide a comprehensive infertility assessment.

4.2.6 TSH - Thyroid Stimulating Hormone

The pituitary gland releases thyroid stimulating hormone, which, along with T3 (Triiodothyronine) and T4 (Thyroxine), assesses thyroid function. High TSH levels indicate an underactive thyroid, while low TSH levels indicate an overactive thyroid.

Thyroid dysfunction impacts male fertility, altering testes function. Hyperthyroidism in men may reduce semen volume and affect sperm shape and movement, while hypothyroidism can lead to abnormalities in sperm shape.

Diet and supplements cannot change thyroid levels; Thyroxine tablets are prescribed by a fertility specialist or endocrinologist.

5. Additional Biomarkers: Uncovering Hidden Factors

Beyond hormones and nutritional status, there are biomarkers that can provide critical insights into your fertility. These tests help paint a more complete picture of your reproductive health.

samples of biomarkers for fertility blood test

5.1 HbA1c and / or Fasting Blood Glucose

Blood glucose (or blood sugar) levels significantly impact fertility, especially in those with type 1 or type 2 diabetes.

Elevated blood glucose affects ovulation in women and reduces sperm quality (motility and DNA integrity) in men, increasing miscarriage risk.

If you have diabetes, check HbA1c, which reflects your blood glucose control over the last three months. High levels of HbA1c show poor control.

Diet plays an important role in managing blood sugar. Focus on a diet rich in whole grains, fruits, and vegetables. Use less processed foods and confectionery.

5.2 Blood Lipids

Blood lipids, which include total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides, are circulating fats.

Abnormal lipids, such as high cholesterol, LDL, triglycerides, and low HDL, are associated with obesity, diabetes, heart disease, PCOS, and semen quality. They can result from insulin resistance, impacting ovarian function and ovulation in women.

Diet plays a key role in improving blood lipid profiles by adjusting fat intake. Focus on polyunsaturated fats and limit saturated and trans fats.

5.3 Omega-3

Omega-3, an essential fatty acid, is crucial for our health since our body can't produce it. DHA (docosahexaenoic acid) and EPA (Eicosapentaenoic acid) are specific forms of Omega-3.

DHA and EPA reduce inflammation, benefiting fertility and lowering the risk of pregnancy loss. They also reduce triglycerides and minimise sperm DNA damage.

These fats are abundant in oily fish and to a lesser extent in eggs, dairy, nuts, and seeds.

To determine your Omega-3 intake, test your Omega-3 index in the blood. It gives you an indication if you are eating enough of these essential fatty acids over a period of time. Vegans, vegetarians, or those on plant-based diets may need supplements.

5.4 CRP- C-Reactive Protein

C-Reactive Protein, produced by the liver, rises in response to injuries, infections, or inflammation.

Infertility is associated with chronic inflammation, as seen in conditions like inflammatory bowel disease, PCOS, and obesity. High CRP levels are linked to reduced pregnancy chances and fertility treatment success.

It's a helpful indicator for your doctor to assess your body's condition and plan further tests. Treating the underlying causes of inflammation is essential.

6. Taking Action: Improving Your Fertility

By analyzing a combination of these tests, you can create a comprehensive fertility profile. This profile will offer a clearer picture of your reproductive health, guiding you in making informed decisions. Whether you're planning to conceive soon or in the future, this is a crucial step towards building a healthy family.

fertility blood test results explaineed by professional

Now that you're armed with knowledge about your fertility, it's time to take action. Learn how lifestyle changes, dietary improvements, and other strategies can boost your reproductive health.

Check out how a fertility dietitian can work with you to transform your diet, improve your nutritional status, balance hormones and address abnormal test levels. Remember, you have the power to enhance your fertility naturally.


Understanding your fertility is the first step towards building a strong foundation for your family's future. Fertility blood tests, tailored for both men and women, offer vital information about your reproductive health. From hormonal balance to nutritional status, these tests provide essential clues to guide you on your next steps on your fertility.

In this comprehensive guide, we've explored a wide range of fertility blood tests, including those for nutritional bloods, hormones, and other biomarkers. We've explained why these fertility blood tests are essential and how they can impact your fertility journey.

Dr Katie Psarou Fertility Dietitian

Dr Katie Psarou, PhD, MSc, BSc (Hons) RD MBDA

UK Registered Fertility and Maternal Health Dietitian

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