Causes of infertility

In response to all the questions patients in the early stages of their IVF journey have asked during his various live events, Professor Charles Kingsland explains some possible causes of infertility and the first steps to getting the right fertility diagnosis.


When you're trying for a baby and are in the right age range, most couples will achieve a pregnancy after about a year of trying. The chances of conception reduce after 18 months, so we normally define infertility as an inability to conceive after 18 months of unprotected sexual intercourse. It's usually at about this time you would want to seek professional advice, either from your GP initially or contacting a dedicated fertility clinic such as your local CARE clinic.

This time limit is variable however, as different people have different needs. For example a woman entering her 30s, her natural fertility starts to decline, slowly at first, then more rapidly over the age of 35 and then very quickly when she reaches the age of 38 and above. Therefore, if a couple have been trying for a shorter length of time but are older, they may wish to contact a clinic more quickly.

There are no hard and fast rules about seeking help because, as many who are suffering or have suffered infertility will know, not being able to have a child at a time in your life when you want to start a family can be very stressful.

Also, you may not have been thinking about starting a family just yet but are inquisitive about your own fertility. In these circumstances, it is perfectly OK to seek advice about having some fertility tests for reassurance. These reassurance tests will not routinely be available to you on the NHS but are readily accessible at your local clinic. Prior knowledge of any problems which may be around is always useful, particularly for women who may be getting a little older.

Once you have sought advice, the Doctor will want to make a diagnosis as to the possible problem, if there is one at all and so will arrange some tests on both male and female in the case of heterosexual couples. Same sex couples and single women will have different needs so the tests would be modified accordingly.


What causes infertility?

There are many potential problems that can cause infertility; but what must be stressed first is that infertility is something which can result from both male and female reproductive issues. 

In the last 80 years or so, the average male sperm count has declined by half. We do not know the main cause of this but it's likely to be due to our environment, what we eat and the changes in our lifestyle. We tend not to move around as much as we used to and this negatively impacts on our sperm counts.

If we look at the other causes, they can be roughly divided into three different categories; an issue with the female's eggs, a structural abnormality in the female’s pelvis, and unexplained infertility.


Female egg quality

Firstly, there may be an egg problem in the female. Women are born with their full complement of eggs. They can’t make more or make them better quality. What we can do however, is to try and preserve the quality of their eggs as we get older.

There is no way you can test the quality of eggs in the ovaries, but you can roughly measure the number. This can be done by a simple blood test which measures a hormone produced by the little cells that surround an egg called Ante Mullerian hormone, often abbreviated to AMH. The more AMH you've got, the more eggs you are likely to have. It's better, however to be younger with a low AMH than older with a higher AMH. Having a high AMH at 40 means that you have a high number of 40 year old eggs but they are less likely to be of high quality as when you were younger.

You can also test potential egg numbers by measuring the Antral Follicle Count (AFC). Antral follicles are little fluid filled sacs in the ovary which can be measured on ultrasound scan. The higher the AFC, generally the more eggs you have.

The next thing we need to know about eggs are if they are being released regularly. A common problem is what we call anovulatory infertility, where the female has eggs but she doesn't release them. Again, a couple of simple tests can check whether eggs are being released at the right time.

A very useful indicator of ovulation however is a female’s periods. If they are regular and predictable, it's highly likely that she is ovulating. If they are irregular or unpredictable, it is less likely. Usually, this can be easily treated, provided there are eggs.


Pelvis structure

Secondly, there may be a structural abnormality in the female’s pelvis, most commonly in the fallopian tubes, which are the main structures which allow the passage of eggs from the ovary and sperm up to the egg.

Fertilisation takes place in these tubes, which can become damaged or blocked by infection, particularly by a bug called Chlamydia which is usually the main culprit.

More importantly, the tiny little hairs lining the tubes, the cilia, can become damaged by infection. These waft in time and very delicately move the eggs and sperm together and then transport the fertilised egg, the embryo, into the uterus where it can implant into the womb lining called the Endometrium. This is where a pregnancy can establish.

An Ultrasound scan can usually pick up any abnormalities in the Uterus, or tubes which may be affecting fertility but occasionally more involved tests may be required to see if the tubes are blocked.


Unexplained infertility

Finally, when all these tests have been performed, it may be that no abnormalities of sperm, egg or uterus have been found. In these cases, a diagnosis of Unexplained Infertility is made.

That doesn't mean to say there is nothing wrong, it just means that the standard tests have not discovered any significant abnormality. It might be that the couple have just not been trying long enough, or at the wrong time in the female’s cycle.

A word of warning here; there are a huge number of tests available to test all sorts of hormones, vitamins and various other substances which may be expensive and of doubtful significance. It is vitally important therefore that you get the right advice about your fertility and testing at this point from a reputable clinic.

The starting point is always to speak to a qualified specialist with expert knowledge in fertility issues, preferably in a designated fertility clinic, local to you, if at all possible. In the vast majority of cases, to make a diagnosis as to the causes of Infertility, the following tests are required;

  • A semen analysis
  • An ultrasound scan of the pelvis
  • An Antral Follicle Count and/or an AMH test

Once a cause has been found, even in cases of Unexplained Infertility it is only then that appropriate treatment, if any is needed, can be started.


If you would like to find out more about your fertility, you can call our new patient enquiry team on 0800 564 2270, they’ll be happy to answer any questions you have and book you a consultation with one of our doctors.

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