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

OBJECTIVE:There has been a widely reported decline in both semen quality and fertility rate, however to date these studies have not looked at a decline of both in the same time period within the same geographical area. The objective of this study was to determine if there existed a temporal trend in both semen parameters and fertility rates for the same geographic area (King County, WA) over time. MATERIALS AND METHODS:Semen parameters from sperm donors at Seattle sperm bank were obtained from 2008 to 2021. Sperm donations occurred in King County, WA. Donors were from within 50 miles of the donation site. Fertility rates were calculated for King County, WA using census data from SEER to find number of women aged 15-49 and the number of births were found using CDC Wonder data from 2006 to 2017. RESULTS:There were a total of 76,622 sperm donor semen analyses from King County, WA included in our study from 2008 to 2021. The fertility rate for King County, WA was calculated from 2006 to 2017. From 2008 to 2021, there was a statistically significant decline in semen quality over time for both sperm count (P < .01), total motile sperm count (P < .01), sperm concentration (P < .01), and progressive motility (P < .01). Additionally, from 2006 to 2017 there was a statistically significant decline in fertility rate (P < .01). CONCLUSION:We report a statistically significant decline in sperm parameters among donors and a corresponding decline in fertility rates from the same geographic area that warrants further investigation given the serious societal and economic impacts a shrinking population presents. While certainly not the sole contributing factor, declining sperm parameters likely need to be accounted for when accounting for declining fertility rates.