Declining sperm counts over the past decades

As this article, “Sperm Counts Continue to Fall,” in the Atlantic points out, sperm counts have been known to be declining for decades, since the early 70s.

Studies have shown that between 1973 and 2011 there was a decrease of 60% or more in total sperm counts and a decrease of more than 50% in sperm counts per milliliter across the globe.  The reasons behind this decline are largely unknown and speculative but include the following possibilities and perhaps a combination of issues:

  1. Phthalates, which are pervasive in plastic products. Obviously, plastic products have been exploding in the world. Microwaving plastics may leach these chemicals that have antiandrogenic (antitestosterone) effects.
  • Estrogen levels increasing in males. We know that overweight males, those with obesity and high percentage of body fat, had increased estrogen levels which may have a negative effect on testicular function and sperm production.
  • “Endocrine disruptors”. These are chemicals that may mimic the effects of estrogen having a similar effect as does number 2 above. Endocrine disruptors may be in various plastics as well as in addition to other chemicals used in the agriculture industry.
  • Insulin resistance. This is a problem that is linked to obesity and percentage of body fat. We all know that insulin resistance and weight issues have been increasing in males since the 70s. 

Other speculative ideas include the use of medications that lower cholesterol. Cholesterol is instrumental for the formation of testosterone.  Obviously, this is helpful in improving cardiovascular factors but in some situations these medications may have a detrimental impact in some individuals regarding testicular function.  Other things like the increased use of soy products, which have weak estrogenic effects, may also be a contributing factor.

Whatever all the causes may be, there is no question that the effect of declining sperm counts and other sperm parameters (motility, morphology, etc.) is a true phenomenon and has a major impact on the male fertility potential.  Adequate and accurate semen assessment is critical as it is more than just quantity that is important and can be affected.  Qualitative sperm assessment is important and should include assessment of DNA fragmentation.  MCRM Fertility has been doing these tests for years and we see that quantitative and qualitative effects are critical for understanding male fertility.  It is not just about count!

Peter M. Ahlering, MD


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