The latest scientific surveys and studies indicate that sperm count in men of the developed world, especially North America, Australia, New Zealand and Europe, have dropped substantially over the years. According to the researchers, in less than 40 years, collective sperm count among western men has declined more than 50%. Sperm count is regarded as a major indication of male fertility.
The new study indicates that men’s sperm counts are on a continued decline. “The results are indeed very profound, and even shocking,” says researcher Dr. Hagai Levine, head of the environmental health track at the Hebrew University-Hadassah Braun School of Public Health and Community Medicine in Jerusalem.
Eventhough the study is not the first to arrive upon such a finding, the researchers say it’s the first ever meta-analysis on the subject. The new findings have limitations—they don't include men from non-Western countries, for one—but the researchers say the study adds to a growing body of research on how changes in environments might be affecting male fertility.
“The impact of the modern environment on health of populations and individuals is clearly huge, but remains largely unknown." says Dr.Levine.
The researchers screened 7,500 studies and found 185 that met their criteria. Studies were included in the analysis if they looked at either men who were unaware of their fertility (for example, men who had never tried to conceive) or men who were deemed fertile (for instance, men known to have conceived a pregnancy). They excluded studies with men who had been included for suspected infertility, such as men attending an IVF clinic.
They found that from 1973 to 2011, there was a steep decline of more than 50% in both sperm concentration and total sperm count among men from Western countries. The researchers also restricted the analysis to studies after 1995 and reported that the decline does not appear to be abating.
“This has been a recognized phenomenon for over 50 years. This is a serious problem” says Dr. Enrique Schisterman, chief of the epidemiology branch at the National Institute of Child Health and Human Development at the the National Institutes of Health and a male fertility expert. (Schisterman was not involved in the study.)
The study did not explain why sperm counts might be down in this group of men, but there are several theories based on prior research performed by the researchers and other groups. Levine says that drops in sperm counts have, in the past, been associated with environment and lifestyle factors including prenatal chemical exposures, adult pesticide exposures, smoking, stress and obesity.
One conclusion that can be arrived upon through the study is that men residing in Western countries were exposed to new manmade chemicals during their life course, and there is more and more evidence that these chemicals hurt their reproductive function. The researchers expressed their hope that their findings should drive massive scientific effort to identify the causes and modes of prevention.
Dr. Schisterman also suspects that environmental factors may be having an impact on the rapid decline of male fertility and not genetics.
Dr. Levine points out that the root causes have to be identified. Moreover, every man can live a healthier life by reducing stress, not smoking, being physically active and keeping a good diet and weight.”