There's a crisis brewing, but it has nothing to do with the economic deficit or the current political uncertainty. Scientists are warning that rising levels of male infertility have become so perilous that it is a serious 'public health issue'. And some go even further.

Professor Niels Skakkebaek, of the University of Copenhagen, describes the issue 'as important as global warming'. Last week, one science writer even suggested, in starkly terrifying terms, that if scientists from Mars were to study the male reproductive system, they would possibly conclude that man was destined for rapid extinction. 

And if it continues, this trend could indicate men are on a path to becoming completely infertile within a few generations. 

Scientists are warning that rising levels of male infertility have become so perilous that it is a serious 'public health issue'

Reports claim that as many as one in five healthy young men between the ages of 18 and 25 produce abnormal sperm counts.

Only 5 to 15 per cent of their sperm is good enough to be classed as 'normal' under World Health organisation rules  -  proving that infertility is not just a female problem. Indeed, among those experiencing difficulty with conception, a male fertility problem is considered important in about 40 per cent of couples.

But women trying to get pregnant are facing another astonishing claim: that the core problems of male fertility  -  while they may be exacerbated by environmental issues  -  start in the womb.

'Sperm counts are declining and there is mounting evidence that the problem starts even before birth,' says Dr Gillian Lockwood, medical director of Midland Fertility Services.

She cites growing evidence that although the process of sperm production  -  known as spermatogenesis  -  starts in adolescence, the crucial preparations are made in the few months before and after birth.