Declining Male Fertility -- Urban Myth Or Alarming Trend?
Lindsay says there are factors that could skew study results, such as the fact that couples are delaying starting a family -- which everyone agrees does affect fertility. There may even be other factors that we may not be aware of -- for example, some of the studies that found declining sperm counts were done in cities.
"People in cities sit down more. That may be a very silly thing, but we know from testicular physiology that testes are meant to be cool, that is why they hang in a little sac outside the body. And we know that if you raise temperature that you can disrupt sperm counts," he says. "Now whether in practice the fact that men wear trousers, they sit down in offices on their testes and keep them warm eight hours a day is enough to cause declining counts, nobody knows."
Other critiques of the studies are the methods used of collecting and analyzing sperm, which may have been different 50 years ago compared to today, says Lindsay, making it like comparing "kilograms to pounds." Additionally, the men who are included in studies, because either they show up at a fertility clinic or agree to be tested, may also skew the results.
"Here we run a fertility service. Now the problem with our database is, of course, the fact that people come to us at all means that they are complaining of fertility problems. So they are a self-selected group," he says. "Getting normal men is quite difficult; there is even the argument that when you are recruiting people, people who are prepared to be recruited don't represent the average."
"The bottom line is that there are some unanswered questions that need to be addressed," says Lipshultz. "But we don't have any data to really say that the incidence increasing. What is increasing is the awareness and the public's desire to get treated."
Some large studies are underway, including one by the World Health Organization (WHO) and another by the Environmental Protection Agency, but results may be years away.
"It is difficult to study global problems without having a total commitment from the various governments and agencies. The WHO is involved, but not that actively involved, and nobody has addressed this issue as aggressively as they need to do it," says Zavos. "More organized studies worldwide should be initiated looking at that question because it is a serious problem, if indeed it is happening, and we don't know about it. They are very serious matters that affect humanity."