The first large study of sperm quality across a whole European country has confirmed that the concentration of sperm is in steady decline.
French researchers studied the sperm from 26,609 partners of women referred for IVF because of blocked Fallopian tubes and found that sperm concentration dropped by 32.2% between 1989 and 2005 at an average of 1.4 million/ml per year.
They also found a significant 33.4% decrease in the mean percentage of sperm with normal morphology over the same 17 year period, with an average decrease of 1.7% normal forms per year in the period from 1998 to 2005.
The issue of declining sperm quality has been controversial with earlier studies criticised for selection bias and poor representation of the population as a whole. But the authors of this study say the results ‘indicate a severe and generalised decrease in semen quality in France’ and that the sample ‘is close to the general population.’
The drop may be due to environmental factors – including the impact of endocrine disruptors during pregnancy – or other factors such as increasing BMI, poor nutrition or infections.
Human Reproduction 2012, available online 5 December