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Infertility means difficulty in conceiving naturally (becoming pregnant) despite having regular unprotected sex when not using contraception. There is no definite cut-off point to say when a couple is infertile. Many couples take several months to conceive. About 84 couples out of 100 conceive within a year of trying. About 92 couples out of 100 conceive within two years. Looking at this another way, about 1 in 7 couples do not conceive within a year of trying. However, more than half of these couples will conceive over the following year, without any treatment.

Doctors usually suggest some tests if a couple has not conceived after one year, despite regular sexual intercourse. Tests or treatment may start earlier if the woman is older, or if there is an obvious reason why a particular couple will not conceive, however long they try.

It is usually worth seeing a GP if you have not conceived after one year of trying. A GP can check for some common causes, talk things over and discuss possible options. You may want to see your GP earlier, if the woman in the couple is over the age of 36 or if either partner has a history of fertility problems.

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What can cause fertility problems?

Older women tend to be less fertile than younger women. The fall off of fertility seems to be greatest once you are past your middle 30s.

  • 92 out of 100 women aged 19-26 trying to conceive will do so within a year.

  • Between the ages of 35 and 39, this drops to 82 out of 100. If the male or female partner is stressed, this can also affect libido and how often the couple has sex.

Ovulation problems in women

Not producing eggs (ovulating) is the cause of problems in about 1 in 4 couples. In some women this is a permanent problem. In some it only happens from time to time: some months ovulation occurs and some months it doesn't. There are various causes of ovulation problems including:

  • Menopause.

  • Premature ovarian insufficiency.

  • Polycystic ovary syndrome (PCOS).

  • Hormone problems (such as hormone imbalance).

  • Being very underweight or overweight.

  • Excessive exercise (such as regular long-distance running) can affect your hormone balance which can affect ovulation.

  • Long-term (chronic) illnesses. Some women with severe chronic illnesses, such as uncontrolled diabetes, cancers and chronic kidney disease, may not ovulate.

  • A side-effect from some medicines. Medicines that sometimes cause this include chemotherapy medicines. Some street drugs such as cannabis and cocaine can also affect your ability to ovulate.

  • Various other problems with the ovary such as certain genetic problems.

Fallopian tube, cervix or uterine problems

These are the cause in about 2 or 3 in 10 couples with infertility. Problems include:

What can cause infertility in men?

Male reproductive organs

Cross-section diagram of the male reproductive organs

In some couples, a condition which might affect fertility is found in the male partner. The most common reason for male infertility is a problem with sperm, due to an unknown cause. The sperm may be reduced in number, less able to swim forwards (less mobile) and/or be abnormal in their form.

There are various risk factors that may affect sperm production and male infertility. These include:


No cause can be found in about 1 in 4 couples with infertility.

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When to see a doctor about infertility

Most GPs are happy to talk through any difficulties that you may have concerning fertility. It is best for both partners to seek medical advice together. It is quite usual for GPs to do the following:

  • Ask how long you have been trying to get pregnant and if you have been pregnant before. (This includes asking the male partner if any previous partner of his has been pregnant before.)

  • Go over your general health and discuss any past illnesses and infections.

  • Ask about any medication or recreational drugs that you may be taking.

  • Ask if you smoke and how much alcohol you drink. Your GP may also discuss your weight.

  • Ask about your occupation.

  • Ask if either partner is feeling stressed at present.

  • Talk about sex and be sure there are no sexual problems. Sometimes people ask their doctor about difficulties with fertility when the real problem is difficulty with sex.

  • Examine both partners. This can include weighing both partners, a pelvic examination for a woman and an examination of the penis and scrotum for a man.

Tests for infertility

Your GP may suggest a few tests. For example:

  • A sperm test (semen analysis) of the male partner.

  • A blood test to check that ovulation occurs in the female partner. This measures the hormone progesterone which is high just after ovulation. The blood sample is taken on the 21st day of a regular 28-day cycle (counting day one as the first day of bleeding).

  • They may also suggest some other tests, depending on any other symptoms that you may have. For example, whether the female partner has regular periods or not, etc. Further blood tests or an ultrasound scan may be helpful in finding out your risk of infertility.

Tests or referral to a doctor who is a specialist are generally not suggested until you have been trying to conceive for 12 months:

  • If the female partner is under the age of 36.

  • If both partners are otherwise healthy.

  • If your GP has not found any problems in the examination or tests that he or she has carried out.

If any of these conditions do not apply, you may be referred earlier to a doctor who is a specialist.

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Some general advice

The success rate of conceiving gradually goes down over time. However, for couples where no cause is found for the problem, there is still a good chance of conceiving without treatment. In such couples, without treatment, about half who do not conceive within one year conceive within the following year. Therefore, the usual pre-conception advice still applies. For example, women are advised to:

  • Take folic acid each day to reduce the chance of a spinal cord problem in a baby.

  • Have a blood test to check that they are immune to German measles (rubella). They will be offered immunisation to rubella if they are not immune.

  • Eat a healthy diet.

See the separate leaflet called Planning to Become Pregnant.

In addition, the following may be relevant to some people:


This can affect fertility in men and women. It has been estimated that in each menstrual cycle, smokers have about two thirds the chance of conceiving compared to non-smokers. Smoking is also harmful to a developing baby if the mother smokes. Therefore, it is a good time for both partners to stop if they are smokers.

Alcohol in excess
This may affect fertility - both for men and for women. The Department of Health recommends that women trying to become pregnant do not drink any alcohol. However, the exact amount of alcohol that is safe during pregnancy is not known. This is why the advice is not to drink at all. If you do choose to drink when trying to become pregnant then limit it to one or two units, once or twice a week. (This is the equivalent of one or two glasses of wine, once or twice a week.) You should never binge drink or get drunk. This is because alcohol may harm a developing baby.


If you take any medication regularly and are thinking about becoming pregnant, discuss this with your doctor in advance. Some medicines can affect a developing baby and may need to be changed before you become pregnant. An important example of this is medicines for epilepsy.


If you have a medical condition which needs regular monitoring, in particular diabetes, it is very important to start planning before you ever become pregnant.

Weight control

You may have a reduced chance of conceiving if you are very overweight or underweight. For the best chance of conceiving, you should aim to have your body mass index (BMI) at between 20 and 30. If appropriate, see your practice nurse to measure your BMI and for advice about diet and weight control. Participating in a group programme involving exercise and dietary advice has been shown to lead to more pregnancies than weight loss advice alone.

Some recreational drugs

Recreational drugs can affect fertility and should be avoided.

Sex and fertility

It is best not to try to time when you have sex to coincide with expected ovulation. This may cause anxiety, which can sometimes lead to sexual or relationship problems.

After a couple has had unprotected sex, sperm survive for up to seven days. Therefore, even though an egg (ovum) only survives for 12-24 hours, having sex two or three times a week is sufficient if you are trying to conceive. Studies have shown that having sex every two to three days is likely to maximise your chance of getting pregnant. You may want to have sex more often, which is fine, but it probably will not increase your chance of conceiving. It is thought that the more relaxed and spontaneous your sex life, the more likely that you will conceive.

The idea behind using temperature charts and ovulation kits to help predict when you are most fertile is that this can help you time when to have sex. However, using methods like this has not been shown in studies to improve your chance of conceiving. It can also cause a lot of stress within a relationship. They are therefore not usually recommended.

Doctors are used to talking about sexual problems. Any worries or concerns in this area are best talked over with your GP.

Infertility treatment

The treatments for infertility will depend on the underlying cause. The treatments, such as fertility drugs, are discussed in a separate leaflet on infertility treatments.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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