Short answer: A semen analysis measures, among other things, volume, sperm concentration, total sperm count, motility, morphology, and vitality. WHO's reference values from 2021 are statistical comparison values derived from fertile men – not a boundary between fertile and infertile. Furthermore, a single sample varies greatly over time, and healthcare providers often request a second sample before interpreting the results.
How a semen analysis is performed
A semen analysis is a central part of a fertility investigation. According to 1177 Vårdguiden, you should have ejaculated two to four days before providing the sample, and then not ejaculate again until it's time to provide it. The sample is usually provided at the clinic or according to the instructions you receive from them, as the time between sample collection and analysis affects the result.
1177 also states that in some cases, you may need to provide two semen samples a few weeks apart. The results are reviewed with a doctor, usually during a joint appointment where the partner's test results are also discussed. Sometimes, the sample is supplemented with an andrological examination, where the doctor, among other things, examines the testicles with ultrasound.
What is measured in the sample?
A basic semen analysis according to the WHO laboratory manual includes several different measurements. Volume indicates how much seminal fluid was provided. Sperm concentration indicates the number of sperm per milliliter, while total sperm count indicates how many sperm are in the entire ejaculate. Motility is divided into progressive motility (sperm moving forward), non-progressive motility, and immotile sperm.
In addition, morphology is assessed, meaning the proportion of sperm with normal shape, as well as vitality – the proportion of live sperm. The laboratory also usually measures pH. Together, these measurements provide a picture of production and function, but they do not tell the whole story: fertilization capacity cannot be fully determined from a laboratory value.
WHO's reference values from 2021 – what they mean
In the sixth edition of the WHO laboratory manual (2021), the lower reference values are based on approximately 3,500 men whose partners became pregnant naturally within twelve months. The values correspond to the fifth percentile in that group, meaning that five percent of fertile men fell below the threshold.
The lower reference values are: volume 1.4 ml, sperm concentration 16 million per ml, total sperm count 39 million per ejaculate, progressive motility 30 percent, normal morphology 4 percent, vitality 54 percent, and pH 7.2. The median values in the same data are significantly higher – for example, 66 million per ml for concentration – which illustrates how wide the normal range is.
It is worth noting that in the sixth edition, WHO deliberately downplayed concepts like "normozoospermia." The reference values are intended as comparison points, not as a definitive answer for who can become a parent. Many men with values below the threshold have children, and values above the threshold are not a guarantee.
Why a single sample is rarely enough
Sperm parameters naturally vary over time in the same person. Illness with fever, prolonged stress, sleep deprivation, medication, and the time elapsed since the last ejaculation can all affect a single sample. Since sperm production takes about three months, a sample also reflects conditions over a period in the past, not just the current state.
This is one of the reasons why healthcare often requests a follow-up sample when the first one is abnormal. An abnormal result should therefore be seen as a piece of the puzzle in an ongoing investigation, not as a final verdict. Providing a sample can feel emotionally charged for many – it is a common reaction and nothing to be ashamed of.
What happens after the test result?
Depending on what the overall investigation shows, healthcare may suggest further investigation, a watchful waiting approach, or treatment such as insemination (IUI) or IVF. In cases of very low values, more specialized investigations may be relevant. Sometimes, no clear cause is found at all, which is more common than many think.
Lifestyle factors such as smoking, alcohol, obesity, and heat exposure are often discussed in connection with the test results. The evidence for how much individual changes affect the outcome is mixed, but there is reasonable support that quitting smoking and an otherwise healthy lifestyle are beneficial for general health. If supplements may be relevant, it is something to check with the clinic handling the investigation.
Frequently asked questions
How long should one abstain from ejaculation before the test?
According to 1177 Vårdguiden, you should have ejaculated two to four days before providing the sample, and then not ejaculate until the time of the test. Always follow the instructions you receive from your clinic, as routines may vary slightly.
Does a value below the reference limit mean I am infertile?
No. The reference values describe how a group of fertile men were statistically distributed, and five percent of them fell below the limit. A low value may indicate reduced fertility, but it is the doctor who weighs all findings in the investigation.
Can sperm quality change over time?
Yes, the values naturally vary between different samples. Since sperm production takes approximately three months, changes in health and lifestyle may only become noticeable after a while. The extent of the effect in individual cases is difficult to predict and the evidence is limited.
This article is general information and does not constitute medical advice. Always consult a doctor or other healthcare professional about your own situation, your test results, and any treatment.
Sources
- Lower reference limits for semen characteristics – WHO laboratory manual for the examination and processing of human semen, Sixth Edition (2021), compiled by Andrology Laboratories, Manchester University NHS Foundation Trust
- Fertility investigation – 1177 Vårdguiden
- Boitrelle F. et al. The Sixth Edition of the WHO Manual for Human Semen Analysis: A Critical Review and SWOT Analysis. Life (Basel). 2021;11(12):1368