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Around half of the causes of fertility problems lie with men, and a semen analysis, also known as a sperm test, is the first line test for men who wish to assess the quality and quantity of their sperm in terms of fertility.

Where do the WHO benchmarks for sperm parameters come from?

The World Health Organisation (WHO) published a paper in 2010, which defined the benchmark parameters for semen analysis. From a sample of 4,500 men who were able to make women naturally conceive within one year of unprotected sex the benchmark was set for the lowest 5% of the sample.


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Imagine a line-up of 100 fertile men; if your results are above man number five you are deemed to be ok, and if your results are below man number five you are deemed to require treatment.

Fertility clinics throughout the world use the WHO benchmark when assessing the fertility of their male patients, typically interpreting it in the following way:

  • Sperm count/concentration: Sperm count is the total number of sperm in the whole ejaculate; and sperm concentration refers to the number of millions of sperm per millimetre of ejaculate. The WHO considers a fertile sperm count to be at least 39 million per ejaculate, with a concentration of 15 million per millilitre.
  • Volume: The most straightforward parameter of the semen analysis is the volume of semen per ejaculation. The WHO considers 1.5 millilitres or more of semen per ejaculation to be healthy.
  • Motility: The sperm’s ability to move in a straight line or large circle is taken into account as healthy sperm should be able to navigate the female reproductive tract and unite with the egg. The WHO benchmark states that at least 40% of the sperm should be motile i.e. moving; any less than 40% and fertility problems could be likely to occur. On top of that, at least 32% should be moving in a straight line.
  • Morphology: The size and shape of the sperm head, mid-piece, and tail is judged by a variety of scoring systems. The WHO benchmark is for a minimum of 4% of sperm to be a healthy shape: oval head and a long tail i.e. normal form. Those with morphological defects may have difficulty in fertilising an egg and fertility treatment may be required.
  • pH: Healthy semen has low acidity; the WHO have set the benchmark at 7.2 pH or higher. Anything lower than that indicates acidic semen which can be caused by obstructed ejaculatory ducts or congenital bilateral absence of the vas deferens, which can occur with cystic fibrosis.

The results of your sperm test should not be interpreted too rigidly. The results are not always black and white; instead they indicate probabilities and poor results may warrant further investigations. There are often a number of factors that combine to cause infertility. Here at TCM our fertility experts are always on hand to help you achieve your dream of becoming parents. Please get in touch today to book a consultation or just have a chat with us, we love to hear from you.

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