A recent study into the sperm concentration of 26,600 men, has shown that the average has dropped since the 1990's.
The findings have been so prominent that experts have urged for action to be taken, to ensure that family sizes do not decrease, and fertility treatment costs do not increase.
The study in France, found that the average sperm count has been on a "significant and continuous" decrease over 17 years of around 32%.
The team worked out that a 35 year old man would see his sperm count per millilitre drop from 73.6 million to 49.9 million, they also found that the number of deformed sperm also increased.
The take-home message from this study is extremely simple - sperm number, and sperm quality has declined progressively over the study period - Professor Sharpe
The authors of the study published it in the Journal of Human Reproduction, and concluded that the findings showed the extent of the "severe and general decrease" in sperm quality and concentration. They went on to say "This constitutes a serious public health warning. The link with the environment particularly needs to be determined".
The scientists worked with 126 fertility clinics throughout France, and analysed semen samples. All the men involved were seeking treatment because he and his partner were experiencing difficulties conceiving.
One of the researchers, Dr Joelle Le Moal, said "The decline in semen concentration shown in our study means that the average values we have for 2005, fall within the 'fertile' range for men according to the definition of the World Health Organisation".
He went on to say "However this is just an average, and there were men in the study who fell beneath the WHO values. The 2005 values are lower than the 55 million per millilitre threshold, below which sperm concentration is expected to influence the time it takes to conceive".
Past studies have also shown the drop in sperm concentration and quality, and they have cited environmental factors as a possible cause.
Dr Le Moal said " Impairments in the quality of human gametes (male sperm and female eggs) can be considered as critical biomarkers of effects for environmental stresses, including endocrine disrupters. Firstly this is because gametes are the very first cells from which human beings are built up during their lifetimes".
He continued with "According to the theories about the developmental origins of health and diseases, early exposures may have an impact in adult life". Even your genetic DNA can inherit these problems for either parent.
Professor Sharpe, from Edinburgh University has said "The take-home message from this study is extremely simple - sperm number, and sperm quality has declined progressively over the study period".
"In the UK this issue has never been viewed as any sort of health priority, perhaps because of doubts as to whether 'falling sperm counts' was real. Now there can be little doubt that it is real, so it is time for action" he added.
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