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Fertility Basics
When am I most fertile?

For 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. 

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:

What fertility tests are given at the Clinic

Your doctor 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:

  • Cervical smear test if you haven’t had one recently.

  • Urine test for chlamydia.

  • 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.

  • 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.

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 doctor 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. For information on what happens at a fertility clinic, see:

Fertility tests for women
Fertility tests for men
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