Infertility is when a couple cannot get pregnant (conceive) despite having regular unprotected sex.

Around 1 in 7 couples may have difficulty conceiving.

About 84% of couples will conceive naturally within a year if they have regular unprotected sex (every 2 or 3 days).

For couples who have been trying to conceive for more than 3 years without success, the likelihood of getting pregnant naturally within the next year is 1 in 4, or less.

Getting help

Some people get pregnant quickly, but for others it can take longer. It's a good idea to see a GP if you have not conceived after a year of trying.

Women aged 36 and over, and anyone who's already aware they may have fertility problems, should see their GP sooner.

They can check for common causes of fertility problems and suggest treatments that could help.

Infertility is usually only diagnosed when a couple have not managed to conceive after a year of trying.

There are 2 types of infertility:

• primary infertility – where someone who's never conceived a child in the past has difficulty conceiving
• secondary infertility – where someone has had 1 or more pregnancies in the past, but is having difficulty conceiving again

Read more about how infertility is diagnosed.

Treating infertility

Fertility treatments include:

• medical treatment for lack of regular ovulation
• surgical procedures such as treatment for endometriosis, repair of the fallopian tubes, or removal of scarring (adhesions) within the womb or abdominal cavity
• assisted conception such as intrauterine insemination (IUI) or IVF

The treatment offered will depend on what's causing the fertility problems and what's available from your local clinical commissioning group (CCG).

Private treatment is also available, but it can be expensive and there's no guarantee it will be successful.

It's important to choose a private clinic carefully. You can ask a GP for advice, and should make sure you choose a clinic that's licensed by the Human Fertilisation and Embryology Authority (HFEA).

Some treatments for infertility, such as IVF, can cause complications.

For example:

• multiple pregnancy – if more than 1 embryo is placed in the womb as part of IVF treatment there's an increased chance of having twins; this may not seem like a bad thing, but it significantly increases the risk of complications for you and your babies
• ectopic pregnancy – the risk of having an ectopic pregnancy is slightly increased if you have IVF

Read more about how infertility is treated.

What causes infertility?

There are many possible causes of infertility, and fertility problems can affect either partner. But in a quarter of cases it is not possible to identify the cause.

Common causes of infertility include:

• lack of regular ovulation (the monthly release of an egg)
• poor quality semen
• blocked or damaged fallopian tubes
• endometriosis – where tissue that behaves like the lining of the womb (the endometrium) is found outside the womb

Risk factors

There are also several factors that can affect fertility.

These include:

• age – fertility declines with age
• weight – being overweight or obese (having a BMI of 30 or over) reduces fertility; in women, being overweight or severely underweight can affect ovulation
• sexually transmitted infections (STIs) – several STIs, including chlamydia, can affect fertility
• smoking – can affect fertility: smoking (including passive smoking) affects your chance of conceiving and can reduce semen quality; read more about quitting smoking
• alcohol – the safest approach is not to drink alcohol at all to keep risks to your baby to a minimum. Drinking too much alcohol can also affect the quality of sperm (the chief medical officers for the UK recommend adults should drink no more than 14 units of alcohol a week, which should be spread evenly over 3 days or more)
• environmental factors – exposure to certain pesticides, solvents and metals has been shown to affect fertility, particularly in men
• stress – can affect your relationship with your partner and cause a loss of sex drive; in severe cases, stress may also affect ovulation and sperm production

There's no evidence to suggest caffeinated drinks, such as tea, coffee and colas, are associated with fertility problems.

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.

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.