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The “quality” of New Zealand men’s ejaculate has halved over the past two decades – The most dramatic drop of any western country.
This worrying news was presented to a gathering of international fertility researchers in Brisbane, Australia, who were told that the sperm volume carried by the average New Zealand man decreased from about 110 million to 50 million wigglers per millilitre, between 1987 and 2007.
Lead researcher Dr John Peek of Fertility Associates, Auckland, commenting on the relegation of NZ men’s sperm from very good to good quality, said:
It’s rather dramatic indeed, and one of the largest seen in studies in other parts of the world.
So large, in fact, that Dr. Peek suggested that if the downward trend continued towards the 20 million sperm per millilitre “danger mark”, New Zealand would “definitely be running into trouble“. However, the biggest drop was seen in the first decade, with a slower decline in more recent years.
The findings, to be published in the New Zealand Medical Journal, are based on sperm quality data from men volunteering as mystery sperm donors. This contrasts with Australia and the United States, where no decline has been seen; and studies from Scotland and France, which show only marginal declines.
The reasons for the sperm crisis are unclear, but Dr Peek suggested that there were two broad theories on sperm quality decline; one being that semen was affected by environmental toxins, diet and modern changes in lifestyle. The other being a consequence of something that happened when the man was a foetus, i.e. what his mother was exposed to, but both theories are still unclear.
Professor Michael Chapman, from IVF Australia, in Sydney, said the trend was “worrying” for New Zealanders, noting that it was to such a degree that the decline was unlikely to be pure chance. Professor Chapman suggested: “Maybe they have something else going on over the Tasman.”
However, Professor Rob McLachlan, director of Andrology Australia, in Melbourne, said any trend was likely to be global, and the jury was still out as several studies were contradictory. He commented:
Global trends are differing so we don’t have a clear picture on this yet.
And then joking:
New Zealand is unlikely to have a different situation unless you consider all the fertile New Zealand men may be heading over here.
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Posted by Jonathan in Biology