Sperm counts may have declined in young university students in Southern Spain

Abstract

Several studies have investigated temporal trends in semen quality in Northern Europe, but none has examined this question in Southern Europe. A prior study conducted in Almeria Province (Southern Spain) reported higher sperm count and concentration among Spanish young men recruited from 2001 to 2002 compared with young men from Northern Europe. The aim of this new study was to examine whether semen quality has changed among Spanish young men in the last decade. In this cross-sectional study, questionnaires and semen samples were collected from 215 healthy young university students from Murcia Region between 2010 and 2011. The 273 men from the Almeria study previously studied were included in a trend analysis of the two populations from Southern Spain. Descriptive statistics were calculated for the Murcia study population and these and semen variables for the Murcia and Almeria study populations were compared. Study methods and population characteristics were similar across the two studies. Therefore, we used multiple linear regression analyses on the combined population (controlling for study centre, age, ejaculation abstinence time, season, smoking, medication during the last 3 months, Body mass index (BMI), presence of varicocoele and prenatal exposure to tobacco) to look for a birth-cohort effect over the combined study period (2001-2011). Sperm concentration and total sperm count declined significantly with year of birth in the pooled analysis (β = -0.04 and β = -0.06, respectively, both p < 0.01). Sperm counts were significantly lower in Murcia study subjects than in the Almeria participants; sperm concentration median (5th-95th) = 44.0 (8.9-129) million/mL vs. 51.0 (5.0-206) million/mL; p < 0.01 and total sperm count = 121 (17.8-400) million vs. 149 (8.0-599) million; p < 0.01. Other semen variables did not differ significantly between the two studies. Our study suggests that total sperm count and sperm concentration may have declined in young Spanish men over the last decade.

Germline and reproductive tract effects intensify in male mice with successive generations of estrogenic exposure

“…Because estrogenic chemicals have become both increasingly common and ubiquitous environmental contaminants in developed countries, the implications for humans are serious. Indeed, it is possible effects are already apparent, with population-based studies from the U.S., Europe, Japan, and China reporting reductions in sperm counts/quality [2,3,5,6,50–53] and male fertility (reviewed in [7]) within a span of several decades.…”

“…For example, a comprehensive analysis in 2000 of data from more than 100 studies in Western countries provided evidence of a decline in human spermatogenesis during the preceding 50 years [1]. More recent longitudinal cross-sectional studies suggest reductions in both sperm count and quality among young men (ages 18–37) in China (2001–2015;[2]), Spain (2001–2011;[3]), France (1989–2005;[4]), Denmark (1996–2010;[5]), and Finland (1998–2006; [6]). Changes in sperm production have coincided with increases in the incidence of other reproductive defects, including hypospadias, cryptorchidism, and testicular germ cell cancers (reviewed in [7]), and the combined spectrum of reproductive effects has been termed testicular dysgenesis syndrome (TDS; [8]).…”

Semen Quality Assessment in Fertile Men in Madrid During the Last 3 Decades

“…A number of authors normalized sperm concentration, motility, and normal forms by logarithmic transformation. 16,17,21,22 Zinaman et al 26 showed differences between results when they were analyzed using data untransformed and transformed to a logarithmic transformation. Stronger relationships were found using log-transformed variables.…”

Environmental Stressors: Is the Sperm Cell Vulnerable or Resilient?

“…Mendiola et al [31] have asserted, through research focused on young University students of Southern Spain, that sperm counts have declined in populations of that region. Several studies have investigated temporal trends in semen quality in Northern Europe, but none has examined this question in Southern Europe where a prior study conducted in Almeria Province (Southern Spain) reported higher sperm.…”

“…Although some recent studies have corroborated this decline in semen quality [31][32][33], others have found no such change [34,35]. The ambiguity on the issue of sperm count decline has been discussed in an interesting review article by Pacey [36].…”