Causes of Infertility

The complex processes involved in egg and sperm production, and fertilisation, create numerous opportunities for something to go wrong.

Infertility is usually defined as the inability of a couple to conceive after one year of unprotected intercourse.

In younger couples, your doctor may encourage you to wait for up to two years before seeking treatment, however women over 35 and anyone with certain medical conditions should seek help earlier.

About 1 in 6 couples will seek help for infertility. Factors causing infertility are generally found in around 40 per cent of females and one third of males. In the remaining cases both partners are found to have reduced fertility or the cause cannot be determined.

  • Sperm potency:
    The vast majority of cases of male infertility are due to a low sperm count, which is generally associated with a high rate of sperm defects (size, shape and movement). Hormonal imbalances related to follicle stimulating hormone (FSH) and luteinising hormone (LH) do occur in men but are not very common. They may affect the development of sperm and account for some sperm abnormalities. There is also evidence to suggest that male sperm counts are declining in some populations. The exact reasons are unclear but are thought to be environmental.
  • Testicular failure:
    Some men are found to have no sperm in their semen. This could be due to a failure to ejaculate or a failure of the testes to produce sperm. The testes may have been damaged due to a poor blood supply, injury or even a case of adult mumps. Other causes include hormonal problems and genetic defects.
  • Vas blockage:
    Damage as a result of infections can prevent the sperm from becoming part of the ejaculate. Occasionally the ejaculate of some men is diverted into the bladder. This is known as ‘retrograde ejaculation’.
  • Sperm antibodies:
    A small group of men actually produce antibodies against their own sperm.
  • Hormonal / ovulation:
    Hormonal imbalances, related to follicle stimulating hormone (FSH) and luteinising hormone (LH) affect follicular development as well as ovulation. Progesterone secretion can also affect the ability to achieve and maintain a pregnancy.
  • Tubal problems:
    Damage to or infection of the fallopian tubes resulting in blockage or impaired motility is another common reason for infertility, preventing the egg from fertilising or travelling into the uterus.
  • Pelvic problems:
    A key problem in the pelvis is endometriosis, where developing cells from the endometrium break away and adhere to the pelvic contents. Up to 70 per cent of women with endometriosis experience some degree of infertility. Fibroids and polyps in the uterus can also impair fertility.
  • Cervix / vaginal problems:
    Structural abnormalities of the vagina or cervix can affect fertility.
  • Frequency:
    A couple may simply not be having intercourse frequently enough to coincide with the woman’s most fertile phase. Sperm can live about 72 hours in a woman’s reproductive tract and only during this time can they fertilise an egg. Eggs can survive for 48 hours post ovulation.
  • Timing:
    Equally, the problem could be due to missing the most fertile phase, particularly where the woman’s cycle is not regular, or is longer or shorter than the average 28 days.
  • Technique:
    Some cases have been found to be related to technique, where the sperm is not deposited high enough in the vagina to have a chance of passing through the cervix.
  • Age:
    Fertility is intimately related to age, especially in women. Women are born with all the eggs they will ever have in their lifetime. This pool of eggs declines continuously throughout her life. The effects can be seen in a woman’s early 30’s and becomes a common problem in women 35 and over. By the time a woman reaches 40 she will have a drastic reduction in her chances of becoming pregnant. This reduction in pregnancy rates is due to fewer available eggs, a reduction in egg quality and chromosomal abnormalities.

Unexplained infertility is a diagnosis of exclusion. Sometimes there is no diagnosis for the type of infertility you have, which is given the term ‘idiopathic’ or unexplained infertility. This means that all other causes within reason have been ruled out. Unexplained infertility can be a very frustrating diagnosis for couples as there is no definable cause to which they can attribute their inability to conceive. Fortunately, treatment options offer a significant improvement in the chance of falling pregnant for couples with unexplained infertility.


The fertility tests that you will require depend on the complexity of your problem. Some common tests for diagnosis are:

  • Blood Tests:
    Hormone Level Check: Follicle Stimulating Hormone (FSH) levels are measured at the beginning of your cycle to give an indication of the supply and quality of the eggs that are developing in your ovaries. Progesterone is sometimes measured on day 21 of a 28-day cycle to assess whether you are ovulating. Prolactin, oestrogen and thyroid hormone levels may also be measured. If a woman’s thyroid gland is underactive it can interfere with ovulation and the quality of eggs produced.
  • Ultrasound Scans:
    Used to assess the anatomy of your ovaries, uterus and developing follicles. Can also be used to exclude any gynaecological abnormalities.
  • Hysterosalpingogram (HSG):
    This is similar to an x-ray and will check whether the cavity of your uterus is normal and if your fallopian tubes are open.
  • Laparoscopy: Laparoscopy is performed by distending the abdomen with gas (to help obtain a good view) followed by the insertion of a fibre-optic telescope through the navel (umbilicus). A careful inspection of your ovaries, uterus and fallopian tubes will give an opportunity to diagnose and to treat any problems that may be preventing pregnancy.
  • Hysteroscopy:
    A direct examination of the interior of your uterus with a telescope. This allows any adhesions or polyps to be seen and, if necessary, removed.
  • Semen Analysis:
    Assessment of sperm count, motility and morphology (shape), carried out on fresh semen.



For more information or queries regarding any of the services offered at Life Fertility Clinic, please contact us.