Editorial Comment: Temporal Trends of Semen Quality and Fertility Rates Over the Course of a Decade: Data From King County, Washington.

There has been a great deal of controversy in recent years regarding concern for declining sperm parameters and male fertility over the late 20th and early 21st centuries. Are sperm concentrations truly dropping at an alarming rate, and if so, does this decline foreshadow an impending epidemic beyond the 1.3 billion people worldwide currently struggling with infertility? In the present study by Miller and colleagues, the mean total sperm count at one large banking facility in Seattle did indeed appear to fall by 100 million over the course of a decade. While the group also reported a decline in birth rates in the same geographical region during the study time period, this finding is subject to numerous sources of bias and can safely be ignored in favor of focusing on the more rigorous and quantitative analysis of semen parameters.