Decline in sperm count and motility in young adult men from 2003 to 2013: observations from a U.S. sperm bank

Summary Controversy exists regarding stability of semen quality over time with papers reporting decrease, increase or stable parameters in heterogeneous populations. The current study examined semen parameters of young adult men from 2003 to 2013 at an urban U.S. sperm bank. Semen parameters were analyzed before and after cryopreservation for a total of 9425 specimens from 489 individuals. Demographic information was obtained from a social and medical history questionnaire. Following 2–3 days abstinence, the specimens were collected at the laboratory and assessed by uniform technicians and techniques. The data were analyzed using generalized linear regression after adjustment for age, days of abstinence, for repeated samples, as well as by the Cochran–Armitage trend test. The within variability was accounted for by the repeated measures model. All p values were two-sided with p < 0.05 considered significant. There was a significant decline in sperm concentration (−3.55, 95% CI −4.87, −2.23; p < 0.001), total motility (−1.23, 95% CI −1.65, −0.82; p < 0.001), total count (−10.75, 95% CI −15.95, −5.54; p < 0.001) and total motile count (−9.43, 95% CI −13.14, −5.73; p < 0.001). There was no significant change in semen volume (0.03, 95% CI −0.02, 0.09; p = 0.2). The post-thaw total motility significantly (−2.30, 95% CI −2.72, −1.87; p < 0.001) decreased with time. Importantly, demographic and lifestyle factors were stable or improved over the study period. There was a decline in age (ptrend = 0.003) and alcohol use (ptrend = 0.005) and an increase in college GPA (Grade Point Average) (ptrend = 0.02). BMI (ptrend = 0.73), educational attainment (ptrend = 0.2), race/ethnicity (ptrend = 0.53), and lifestyle habits (weekly exercise, ptrend = 0.21; smoking, ptrend = 0.99; marital status, ptrend = 0.85) remained constant. Uniform technicians and techniques over the study period make measurement bias unlikely. This report demonstrates a decline in semen quality among young adult men in the Boston area who were attending or completed a college education during the past 10 years, and requires further study.