Male infertility is now the main cause of couples failure to conceive in around 40% of cases. The number of sperm produced is in decline. Several large studies in Britain, Europe and North America have demonstrated this. In 1992 the Danish Scientist Niels Shakkeback reviewed all the published studies of sperm counts from around the world, involving 15,000 men, in 61 studies, dating back to 1938. He found a fall in the average sperm count of no less than 42%. He also found that sperm quality (mobility and shape) had also significantly declined.

In Britain sperm count is falling by around 2% a year at present. The logic of this decline suggests that by the middle of the next century men may be producing no sperm at all!

Short-term causes of a reduction in sperm productions include :

Scientists are not agreed on what the longer term causes are. The most likely explanation of declining male fertility is the presence in the environment which are similar to oestrogen. It is believed that high levels of oestrogen in the environment are being absorbed by the mother and passed on through the placenta to the foetus.

Many synthetic oestrogens are still widely used as growth promoters in livestock. Oestrogens also enter the ecosystem through their use in Hormone Replacement Therapy.