Infertility can be caused by many different things. For 1 in 4 couples, a cause cannot be identified.

Infertility in women

Infertility is commonly caused by problems with ovulation (the monthly release of an egg from the ovaries).

Some problems stop an egg being released at all, while others prevent an egg being released during some cycles but not others.

Ovulation problems can be a result of: 

• polycystic ovary syndrome (PCOS)
• thyroid problems – both an overactive thyroid gland and an underactive thyroid gland can prevent ovulation
• premature ovarian failure – where the ovaries stop working before the age of 40

Scarring from surgery

Pelvic surgery can damage and scar the fallopian tubes, which link the ovaries to the womb.

Cervical surgery can also sometimes cause scarring or shorten the neck of the womb (the cervix).

Cervical mucus problems 

When you're ovulating, mucus in your cervix becomes thinner so sperm can swim through it more easily. If there's a problem with the mucus, it can make it harder to conceive.

Fibroids

Non-cancerous growths called fibroids in or around the womb can affect fertility. In some cases, they may prevent a fertilised egg attaching itself in the womb, or they may block a fallopian tube.

Endometriosis

Endometriosis is a condition where small pieces of the womb lining (the endometrium) start growing in other places, such as the ovaries.

This can damage the ovaries or fallopian tubes and cause fertility problems.

Pelvic inflammatory disease

Pelvic inflammatory disease (PID) is an infection of the upper female genital tract, which includes the womb, fallopian tubes and ovaries.

It's often caused by a sexually transmitted infection (STI). PID can damage and scar the fallopian tubes, making it virtually impossible for an egg to travel down into the womb.

Sterilisation

Some women choose to be sterilised if they do not want to have any more children.

Sterilisation involves blocking the fallopian tubes to make it impossible for an egg to travel to the womb.

It's rarely reversible – if you do have a sterilisation reversed, you will not necessarily be able to have a child.

Medicines and drugs 

The side effects of some types of medicines and drugs can affect your fertility. These include:

• non-steroidal anti-inflammatory drugs (NSAIDs) – the long-term use or a high dosage of NSAIDs, such as ibuprofen or aspirin, can make it more difficult to conceive
• chemotherapy – medicines used for chemotherapy can sometimes cause ovarian failure, which means your ovaries will no longer be able to function properly
• neuroleptic medicines – antipsychotic medicines, often used to treat psychosis, can sometimes cause missed periods or infertility
• spironolactone – a type of medicine used to treat fluid retention (oedema); fertility should recover around 2 months after you stop taking spironolactone

Illegal drugs, such as marijuana and cocaine, can seriously affect fertility and make ovulation more difficult.

Infertility in men

Semen and sperm

A common cause of infertility in men is poor-quality semen, the fluid containing sperm that's ejaculated during sex.

Possible reasons for abnormal semen include:

• a lack of sperm – you may have a very low sperm count or no sperm at all
• sperm that are not moving properly – this will make it harder for sperm to swim to the egg
• abnormal sperm – sperm can sometimes be an abnormal shape, making it harder for them to move and fertilise an egg

Many cases of abnormal semen are unexplained.

There's a link between increased temperature of the scrotum and reduced semen quality, but it's uncertain whether wearing loose-fitting underwear improves fertility. 

Testicles

The testicles produce and store sperm. If they're damaged, it can seriously affect the quality of your semen.

This can happen as a result of:

• an infection of your testicles
• testicular cancer
• testicular surgery
• a problem with your testicles you were born with (a congenital defect)
• when 1 or both testicles has not descended into the scrotum (the loose sac of skin that contains your testicles (undescended testicles))
• injury to your testicles

Sterilisation

Some men choose to have a vasectomy if they do not want children or any more children. 

It involves cutting and sealing off the tubes that carry sperm out of your testicles (the vas deferens) so your semen will no longer contain any sperm.

A vasectomy can be reversed, but reversals are not usually successful.

Ejaculation disorders

Some men experience ejaculation problems that can make it difficult for them to release semen during sex (ejaculate).

Hypogonadism

Hypogonadism is an abnormally low level of testosterone, the male sex hormone involved in making sperm.

It could be caused by a tumour, taking illegal drugs, or Klinefelter syndrome (a rare syndrome involving an extra female chromosome).

Medicines and drugs

Certain types of medicines can sometimes cause infertility problems. These include:

• sulfasalazine – an anti-inflammatory medicine used to treat conditions such as Crohn's disease and rheumatoid arthritis; sulfasalazine can decrease the number of sperm, but its effects are temporary and your sperm count should return to normal when you stop taking it
• anabolic steroids – are often used illegally to build muscle and improve athletic performance; long-term abuse of anabolic steroids can reduce sperm count and sperm mobility
• chemotherapy – medicines used in chemotherapy can sometimes severely reduce sperm production
• herbal remedies – some herbal remedies, such as root extracts of the Chinese herb Tripterygium wilfordii, can affect the production of sperm or reduce the size of your testicles

Illegal drugs, such as marijuana and cocaine, can also affect semen quality.

Unexplained infertility

In the UK, unexplained infertility accounts for around 1 in 4 cases of infertility. This is when no cause can be identified in either partner.

If a cause for your fertility problems has not been found, talk to your doctor about the next steps.

The National Institute for Health and Care Excellence (NICE) recommends that women with unexplained infertility who have not conceived after 2 years of having regular unprotected sex should be offered IVF treatment.

The NICE guidance has more about unexplained infertility.

Find out more about fertility tests and how problems are diagnosed.

More than 8 in 10 couples, where the woman is under 40, will conceive naturally within a year of having regular unprotected sex.

Regular unprotected sex means having sex every 2 to 3 days without using contraception.

When to get medical help

See your GP if you have not conceived after a year of trying.

You should see a GP sooner if:

• you are female and are aged 36 or over – the decline in fertility speeds up when reaching your mid-30s
• have any other reason to be concerned about your fertility, for example, if you've had treatment for cancer or you think you might have had a sexually transmitted infection (STI)

Fertility tests can take time and female fertility decreases with age, so it's best to make an appointment early.

The GP will be able to do an initial assessment to check for things that may be causing your fertility problems and advise you about what to do next.

It's always best for both partners to visit the GP as fertility problems can affect either or both partners.

Trying to conceive can be an emotional process, so it's important to support each other as much as possible. Stress is just one factor that can affect fertility.

Questions your doctor may ask

The GP will ask you about your medical and sexual history.

Previous pregnancies and children

If you're a woman, the GP will discuss any previous births and any complications with previous pregnancies.

They'll also ask about any miscarriages you've had.

If you're a man, you'll be asked whether you've had any children from previous relationships.

Length of time trying to conceive

The GP will ask how long you've been trying to conceive.

About 84% of people will conceive within 1 year if they have regular unprotected sex (every 2 to 3 days).

Of those who do not conceive in the first year, about half will conceive in the second year.

If you're under 40 and have not been trying for a baby for very long, you may be advised to keep trying for a little longer.

Sex

You'll be asked how often you have sex and whether you have any difficulties during sex.

You may feel uncomfortable or embarrassed discussing your sex life with the GP, but it's best to be open and honest.

If the fertility problem is related to sex, it might be overcome easily.

Length of time since stopping contraception

You'll be asked about the type of contraception you previously used and when you stopped using it.

It can sometimes take a while for some types of contraception to stop working and this may be affecting your fertility.

Medical history and symptoms

The GP will discuss any medical conditions you have or had in the past, including sexually transmitted infections (STIs).

If you're a woman, the GP may ask if you have regular periods and whether you experience any bleeding between periods or after sex.

Medicine

Some medicines can affect your fertility. The GP will ask you about any medicine you're taking and might discuss alternative treatments with you.

You should mention any non-prescription medicine you're taking, including herbal remedies and supplements.

Lifestyle

Several lifestyle factors can affect your fertility. The GP will want to know:

• if you smoke
• how much you weigh
• how much alcohol you drink
• whether you take any illegal drugs
• if you're stressed

They may recommend making changes to your lifestyle to increase your chances of conceiving.

Read more about:

• How can I increase my chances of becoming pregnant?
• How can I improve my chances of becoming a dad?

After asking you questions, the GP may do a physical examination or refer you for tests.

Physical examination

If you are female, the GP may:

• weigh you to see if you have a healthy body mass index (BMI)
• examine your pelvic area to check for infection, lumps or tenderness, which could be a sign of fibroids, ovarian tumours, endometriosis or pelvic inflammatory disease (PID) – see causes of infertility

If you are male, the GP may check your:

• testicles to look for any lumps or deformities
• penis to look at its shape, structure and any obvious abnormalities

After a physical examination, you may be referred to a specialist infertility team at an NHS hospital or fertility clinic for further tests.

Fertility tests for women

Tests to find out the cause of infertility in women include:

Blood tests

Samples of your blood can be tested for a hormone called progesterone to check whether you're ovulating.

The timing of the test is based on how regular your periods are.

If you have irregular periods, you'll be offered a test to measure hormones called gonadotrophins, which stimulate the ovaries to produce eggs.

Chlamydia test

Chlamydia is an STI that can affect fertility. A swab – similar to a cotton bud, but smaller, soft and rounded – is used to collect some cells from your cervix to test for chlamydia.

A urine test may be used as an alternative.

You'll be prescribed antibiotics if you have chlamydia.

Ultrasound scan

An ultrasound scan can be used to check your ovaries, womb (uterus) and fallopian tubes. Certain conditions that can affect the womb, such as endometriosis and fibroids, can prevent pregnancy. 

A scan can also be used to look for signs that your fallopian tubes (the tubes that connect the ovaries and the womb) may be blocked, which may be stopping eggs from travelling along the tubes and into the womb. 

If the ultrasound suggests a possible blockage, your doctor will refer you to a specialist to discuss further checks, such as a laparoscopy.

During a transvaginal ultrasound scan, an ultrasound probe is placed in your vagina. The scan can be used to check the health of your womb and ovaries and for any blockages in your fallopian tubes.

A hysterosalpingo-contrast-ultrasonography is a special type of ultrasound scan sometimes used to check the fallopian tubes.

A small amount of fluid is injected into your womb through a tube put into the neck of your womb (the cervix). 

Ultrasound is used to look at the fluid as it passes through the fallopian tubes to check for any blockages or abnormalities.

If the test suggests a possible blockage, your doctor will refer you to a specialist to discuss further checks, such as laparoscopy.

X-ray

A hysterosalpingogram is an X-ray of your womb and fallopian tubes after a special dye has been injected.

It can be used to find blockages in your fallopian tubes, which may be stopping eggs travelling along the tubes and into your womb.

Laparoscopy

Laparoscopy (keyhole surgery) involves making a small cut in your lower tummy so a thin tube with a camera at the end (a laparoscope) can be inserted to examine your womb, fallopian tubes and ovaries.

Dye may be injected into your fallopian tubes through your cervix to highlight any blockages in them.

Laparoscopy is usually only used if it's likely that you have a problem – for example, if you've had an episode of pelvic inflammatory disease (PID) in the past, or if scans suggest a possible blockage of one or both of your tubes.

Fertility tests for men

Tests to find out the cause of infertility in men include:

Semen analysis

This is to check for problems with sperm, such as a low sperm count or sperm that are not moving properly.

Chlamydia test

A sample of your urine will be tested to check for chlamydia, as it can affect fertility.

Your GP will prescribe antibiotics if you have chlamydia.

Read about the different treatments for infertility.

If you have fertility problems, the treatment you're offered will depend on what's causing the problem and what's available from your local clinical commissioning group (CCG).

Find your local clinical commissioning group (CCG).

There are 3 main types of fertility treatment:

• medicines
• surgical procedures
• assisted conception – including intrauterine insemination (IUI) and in vitro fertilisation (IVF)

Medicines

Common fertility medicines include:

• clomifene – encourages the monthly release of an egg (ovulation) in women who do not ovulate regularly or cannot ovulate at all
• tamoxifen – an alternative to clomifene that may be offered if you have ovulation problems
• metformin – is particularly beneficial for women who have polycystic ovary syndrome (PCOS)
• gonadotrophins – can help stimulate ovulation in women, and may also improve fertility in men
• gonadotrophin-releasing hormone and dopamine agonists – other types of medicine prescribed to encourage ovulation in women

Some of these medicines may cause side effects, such as nausea, vomiting, headaches and hot flushes.

Speak to your doctor for more information about the possible side effects of specific medicines.

Medicine that stimulates the ovaries is not recommended for women with unexplained infertility because it has not been found to increase their chances of getting pregnant.

Surgical procedures

There are several types of surgical procedures that may be used to investigate fertility problems and help with fertility.

Fallopian tube surgery

If your fallopian tubes have become blocked or scarred, you may need surgery to repair them.

Surgery can be used to break up the scar tissue in your fallopian tubes, making it easier for eggs to pass through them.

The success of surgery will depend on the extent of the damage to your fallopian tubes.

Possible complications from tubal surgery include an ectopic pregnancy, which is when the fertilised egg implants outside the womb.

Endometriosis, fibroids and PCOS

Endometriosis is when parts of the womb lining start growing outside the womb.

Laparoscopic surgery is often used to treat endometriosis by destroying or removing fluid-filled sacs called cysts.

It may also be used to remove submucosal fibroids, which are small growths in the womb.

If you have polycystic ovary syndrome (PCOS), a minor surgical procedure called laparoscopic ovarian drilling can be used if ovulation medicine has not worked.

This involves using either heat or a laser to destroy part of the ovary.

Read more about laparoscopy.

Correcting an epididymal blockage and surgery to retrieve sperm

The epididymis is a coil-like structure in the testicles that helps store and transport sperm.

Sometimes the epididymis becomes blocked, preventing sperm from being ejaculated normally. If this is causing infertility, surgery can be used to correct the blockage.

Surgical extraction of sperm may be an option if you:

• have an obstruction that prevents the release of sperm
• were born without the tube that drains the sperm from the testicle (vas deferens)
• have had a vasectomy or a failed vasectomy reversal

Both operations take a few hours and are done under local anaesthetic as outpatient procedures.

You'll be advised on the same day about the quality of the tissue or sperm collected.

Any sperm will be frozen and placed in storage for use at a later stage.

Assisted conception

Intrauterine insemination (IUI)

Intrauterine insemination (IUI), also known as artificial insemination, involves inserting sperm into the womb via a thin plastic tube passed through the cervix.

Sperm is first collected and washed in a fluid. The best quality specimens (the fastest moving) are selected.

Read more about IUI.

In vitro fertilisation (IVF)

In vitro fertilisation (IVF), is when an egg is fertilised outside the body. Fertility medicine is taken to encourage the ovaries to produce more eggs than usual.

Eggs are removed from the ovaries and fertilised with sperm in a laboratory. A fertilised egg (embryo) is then returned to the womb to grow and develop.

Read more about IVF.

Egg and sperm donation

If you or your partner has an infertility problem, you may be able to receive eggs or sperm from a donor to help you conceive. Treatment with donor eggs is usually done using IVF.

Anyone who registered to donate eggs or sperm after 1 April 2005 can no longer remain anonymous and must provide information about their identity.

This is because a child born as a result of donated eggs or sperm is legally entitled to find out the identity of the donor when they become an adult (at age 18).

Further information

Get more information about fertility treatment options from the Human Fertilisation and Embryology Authority (HFEA) website.

Eligibility for fertility treatment on the NHS

Fertility treatment funded by the NHS varies across the UK. Waiting lists for treatment can be very long in some areas.

The eligibility criteria can also vary. A GP will be able to advise about your eligibility for treatment, or you can contact your local clinical commissioning group (CCG).

If the GP refers you to a specialist for further tests, the NHS will pay for this. All patients have the right to be referred to an NHS clinic for the initial investigation.

Going private

If you have an infertility problem you may want to consider private treatment. This can be expensive, and there's no guarantee of success.

It's important to choose a private clinic carefully.

You should find out:

• which clinics are available
• which treatments are offered
• the success rates of treatments
• the length of the waiting list
• the costs

Ask for a personalised, fully costed treatment plan that explains exactly what's included, such as fees, scans and any necessary medicine.

Choosing a clinic

If you decide to go private, you can ask a GP for advice. Make sure you choose a clinic licensed by the HFEA. 

The HFEA is a government organisation that regulates and inspects all UK clinics that provide fertility treatment, including the storage of eggs, sperm or embryos.

Complementary therapy

There's no evidence to suggest complementary therapies for fertility problems are effective.

The National Institute for Health and Care Excellence (NICE) states further research is needed before such interventions can be recommended.