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Declining sperm counts in western men

The question of whether sperm counts have been declining over recent decades remains controversial.

Many studies of varying quality have been done in a wide variety of populations but none have provided a definitive answer.

Professor Rob McLachlan

A study published in Human Reproduction Update reports a meta-analysis of studies from around the world that have measured sperm count or sperm concentration over time, on semen samples collected between 1973 and 2011. The authors report a 50% decline in sperm counts over time in men from western countries.

According to Andrology Australia Director, Prof Rob McLachlan, although at first glance this decline seems alarming, it should be noted that “examining for trends in semen quality is extremely challenging as one needs to find a way of assessing whole populations (not just selected men) using consistent analytical procedures over decades.” Prof McLachlan goes on to say, “Ultimately the concern is that a fall in sperm output will be reflected in delays in natural conception rates. To date this has not been established.”

The study does not answer the question of the causes of declining sperm counts, such as increased rates of obesity and exposure to chemicals, most pronounced in western populations. Prof McLachlan made the observation that, “This meta-analysis will no doubt increase the debate about health and environmental impacts on male reproductive health.”

Read more in our journal article reviews.

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