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Research findings

Hidden damage to sperm

Published Updated

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Sperm quality among Western men is poor - especially in Norway and Denmark. It is disturbing that one in five Norwegian men has a sperm quality close to the limit which the World Health Organisation associates with reduced fertility. Research at the Norwegian Institute of Public Health (NIPH) in 2010 helped to reveal the causes of impaired sperm quality.

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The average age of both first-time mothers and fathers is increasing, which can lead to naturally lower fertility levels. It is becoming more common to try assisted reproduction. Failure to conceive can be due to the man, even though the sperm appears normal. A pregnancy may start even if the fertilising sperm is damaged, but the damage in the sperm DNA may prevent the fertilised egg from developing normally.

In addition to age there are environmental factors and lifestyle contributing to the negative trend in male fertility, suggesting the importance of being able to identify such factors. However, it is not straightforward to detect changes in sperm DNA.

“It is obvious that DNA damage present in sperm is of great significance for both fertility and the baby, but can be difficult to detect. We often do not know the reasons why the sperm is damaged,” said Gunnar Brunborg and Ville Sipinen at the NIPH.

New methods

The NIPH’s Department of Chemical Toxicology is examining the relationship between environment, lifestyle and damage to sperm. This research is done in collaboration with the University of Bradford in England, the University of Belfast in Northern Ireland and the University of Maastricht in the Netherlands.

By allowing the sperm to swim in a "sea of chemicals” in the laboratory, the sperm DNA is damaged and new methodologies are tried out to measure such damage.

“It is amazing what sperm can tolerate in the laboratory. But if we compare sperm samples from smokers and non-smokers, there are quite significant differences to the smokers' disadvantage. Men should stop smoking at least 3 months before conception, if they want to improve their sperm quality,” said Brunborg and Sipinen.


  • V.Sipinen, J.Laubenthal, A.Baumgartner, E.Cemeli, J.O.Linschooten, R.W.Godschalk, F.J.Van Schooten, D.Anderson, G.Brunborg. In vitro evaluation of baseline and induced DNA damage in human sperm exposed to benzo[a]pyrene or its metabolite benzo[a]pyrene-7,8-diol-9,10-epoxide, using the comet assay, Mutagenesis (2010) 25(4):417-425.
  • L.Simon, G.Brunborg, M.Stevenson, D.Lutton, J.McManus, S.E.Lewis. Clinical significance of sperm DNA damage in assisted reproduction outcome, Hum Reprod. (2010) 25(7):1594-1608.