Infertility is when a couple can't 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've been trying to conceive for more than 3 years without success, the likelihood of getting pregnant naturally within the next year is 25% or less.

Getting help

Some women get pregnant quickly, but for others it can take longer. It's a good idea to see your GP if you haven't 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 only usually diagnosed when a couple haven't 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 – this may be intrauterine insemination (IUI) or in vitro fertilisation (IVF)

The treatment offered will depend on what's causing your 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 your GP for advice, and should make sure you choose a clinic that's licensed by the Human Fertilisation and Embryology Authority (HFEA).

Read more about how infertility is treated.

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

What causes infertility?

There are many possible causes of infertility, and fertility problems can affect either the man or the woman. But in a quarter of cases it isn't possible to identify the cause.

In women, common causes of infertility include:

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

In men, the most common cause of infertility is poor-quality semen.

Risk factors

There are also a number of factors that can affect fertility in both men and women.

These include:

• age – female fertility and, to a lesser extent, male fertility decline with age; in women, the biggest decrease in fertility begins during the mid-30s
• 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 in both sexes: smoking (including passive smoking) affects a woman's chance of conceiving, while in men there's an association between smoking and reduced semen quality; read more about quitting smoking
• alcohol – for women planning to get pregnant, the safest approach is not to drink alcohol at all to keep risks to your baby to a minimum; for men, drinking too much alcohol can affect the quality of sperm (the chief medical officers for the UK recommend men and women 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.

To find out more about what you can do to protect your fertility, see:

• Protect your fertility
• How can I increase my chances of getting pregnant? 
• How can I improve my chances of becoming a dad?