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Fertility basics

When am I most fertile?

A woman holds a pregnancy test worried about her fertilityFor a woman to become pregnant:

  • intercourse must take place around the time when an egg is released from the ovary
  • the systems that produce eggs and sperm have to be working at optimum levels
  • the fallopian tubes must be open and healthy. 

Eggs live (and can be fertilised) for 12–24 hours after being released, and sperm can stay alive and active in your body for 12–48 hours after ejaculation, so you don’t have to have intercourse at the exact moment of ovulation to get pregnant.

It just takes one sperm to fertilise the egg for you to become pregnant. Although millions of sperm are released upon ejaculation, few survive the journey through the cervix, uterus and fallopian tubes.

If fertilisation does not take place, or if the fertilised egg does not attach itself to the endometrium lining of the uterus, it breaks down, the endometrium is shed and you have a period.  

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How usual is it to have problems conceiving?

80% of couples who have regular sexual intercourse (that is, every two to three days) and who do not use contraception will get pregnant within a year.

The majority of the remaining 20% achieve a pregnancy within two years of trying. 

An estimated one in seven couples has difficulty conceiving. There are several possible reasons why it may not be happening naturally. In men, a fertility problem is usually because of low numbers or poor quality of sperm.

Women become less fertile as they get older. For women aged 35, about 95% who have regular unprotected sexual intercourse will get pregnant after three years of trying. For women aged 38, only 75 % will do so. The effect of age upon men’s fertility is less clear.

Your lifestyle can affect your chances of conceiving, particularly if you are a heavy smoker and are significantly over- or underweight.

Problems affecting women include damage to the fallopian tubes and endometriosis and erratic or absent ovulation.

Sometimes infertility problems can be due to a combination of factors.  In a third of cases, a clear cause is never established.

For more information on possible causes of infertility, see:

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Where can I get help?

A woman discusses her fertility concerns with her GPIf you have not been able to get pregnant after two years of regular, unprotected sexual intercourse, either one or both of you may have a fertility problem.

However, you don’t need to wait that long to seek help.

If you are concerned about not being pregnant, see your GP, who can take a medical history, give you a physical examination and may recommend some tests or lifestyle changes.

If you have been trying to get pregnant for over a year, you should also be offered a test to check that you are ovulating and your partner should be offered tests to check his sperm.

If these tests don’t reveal a problem, you should be offered further tests to check that your fallopian tubes are not blocked.

If one or both of you have a condition that affects fertility you may be offered these tests sooner.

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What fertility tests are given at the GP’s surgery?

Your GP will listen to your concerns, make a note of your medical history and give you a physical examination. This is usually followed by a few basic tests, which can include:

Fertility tests for women

  • Cervical smear test if you haven’t had one recently.
  • Urine test for chlamydia, which can block your fallopian tubes, preventing you from becoming pregnant.
  • Blood test to see if you are ovulating. This is done by measuring progesterone in a blood sample taken  seven days before your period is due.
  • Blood test to check for German measles (Rubella) which, if contracted during the first three months of pregnancy, can harm your unborn baby.
  • Blood test during your period to check for hormone imbalances –measurement of FSH (follicle stimulating hormone, LH (luteinising hormone) and oestradiol. This test can also identify possible early menopause as a cause of subfertility.

Fertility tests for men

  • Sperm test to check for abnormalities.
  • Urine test for chlamydia, which, in addition to being a known cause of infertility in women, can also affect sperm function and male fertility.

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After your initial fertility tests - what happens next?

The next step depends on your test results:

  • If your test results are normal and you have been trying for a baby for less than 18 months, your GP may suggest you make a few lifestyle changes and continue trying to conceive naturally.


  • If the tests reveal a possible fertility issue, especially if you are in your thirties or older, they may make an appointment for you to see a specialist for further tests and possible treatment at your local hospital or fertility unit. For information on what happens at a fertility clinic, see:

All UK citizens are eligible for basic fertility investigations from the NHS. NHS is increasingly also covering the costs of infertility treatments, including IVF, although eligibility criteria apply.

Most Primary care trusts (PCTs) will not support those who already have children living with them, those who have been sterilized in the past, those who are obese or women over 39, for example.

Your GP will be able to explain the local eligibility criteria. Those who are ineligible for NHS treatment may have to pay a private clinic for treatment.

Related links: fertility treatments

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Page last updated: 04 August 2014

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