A massive meta-analysis of 185 types of research conducted over 40 years has discovered 50 percent decline in the overall sperm count and sperm concentration in men from North America, New Zealand, and Australia. The decline occurs at a consistent rate and should be a cause for concern if it continues.

The recent study tries to correct these limitations; it includes data collected from 1973 in a bid to cut down uncertainty in results, unlike other analyses that utilize data since 1931. Also, Meta-regression models were put in place to compensate for variable factors like abstinence, age, and selection of the study sample.

The study

The results were from 42,935 men from two distinct geographical regions – Western (Europe, North America, New Zealand and Australia) and other (Asia, Africa, and South America). A sharp decline was observed in both sperm concentration and sperm count across men in the Western countries. Unlike the Western countries, other geographic groups didn’t exhibit such although the researchers had limited data for non-western countries.

The study lead author, Dr. Hagai Levine said that the recent survey is a wake-up call for health authorities and researchers to look into the possible causes of such sharp decline in sperm count and concentration. And in the end, give out possible preventive methods because sperm counts are vital in the human health and male fertility.

While the study didn’t analyze the possible cause of the steep decline, the researchers suggested that the disruption of endocrine organs from chemical exposures or maternal smoking during pregnancy may have a role to play in prenatal life. Likewise, exposure to pesticides and lifestyle changes may play a role in adult life.

Limitations of the experimental data

It’s good to know the limitations of the data despite the implications of the research. While there is a decrease in sperm count, it doesn’t indicate infertility because the study didn’t consider the motility of sperm which is necessary for fertility.

The study only identified a 53.4 percent decline in the sperm concentration of western men. It doesn’t indicate total infertility in western men. While the study data showed a drop from 99 million per milliliter in 1973 to 47 million per milliliter in 2011, the standards of the World Health Organization says that any volume above 15 million sperm per milliliter is normal.

However, we’re not close to fertility crisis, but the study shows there may be broader issues that will come to play.