Introduction

Three meta-analyses (Carlsen et al., 1992; Swan et al., 2000; Levine et al., 2017) and several single-center studies (Auger et al., 1995; Jorgensen et al., 2001, 2011; Rolland et al., 2012; Mendiola et al., 2013) have reported a decrease in sperm counts in Western countries during both the 20th and 21st centuries. Some have also reported a concomitant downward trend in testosterone levels among men (Andersson et al., 2007; Travison et al., 2009; Nyante et al., 2012). These negative trends may be the consequence of environmental and lifestyle factors that may directly contribute to diminished testicular function, such as increased exposure to endocrine disrupting chemicals (Bergman et al., 2013; Hauser et al., 2015), higher prevalence of obesity (Finucane et al., 2011; Sermondade et al., 2013), deteriorating […]