(300) Systematic Review and Meta-analysis of Seasonal Variation on Human Semen Quality in the United States

Abstract

Abstract Introduction Different environmental exposures such as daylight hours and temperature influence spermatogenesis, which vary across seasons. However, studies on the variation of semen analysis across different seasons reported inconsistent results. Objective To investigate the seasonality of human semen parameters in the United States through a systematic review and meta-analysis. Methods We systematically searched PubMed, Scopus, and Web of Science for studies on seasonal variation of human semen parameters in the United States from conception to December 11, 2022, without language restriction, and also scrutinized the reference list of included studies for any additional related study. We determined the pooled standardized mean difference (SMD) and its 95% confidence interval (95%CI) between seasons using the random effect model in a case of substantial heterogeneity (I2 index≥50%) and the fixed-effect model in a case of low heterogeneity (I2 index<50%) in STATA version 17. The methodological quality was checked using Newcastle–Ottawa Quality Assessment Scale (NOS). Results Our search yielded 548 studies. After screening, 7 studies on 131,306 semen analyses were included for meta-analysis. All included studies had high methodological quality (NOS ≥ 7). Figure 1 shows the pooled SMD of semen parameters between seasons. Semen analysis in winter had a higher volume than those in spring (p-value=0.010; I2=4.63%). Winter had better semen quality than summer in terms of concentration (p-value=0.014; I2=0%) and total sperm count (p-value=0.044; I2=47.80%). Semen quality was also better in winter than in fall, in terms of volume (p-value=0.001; I2=0%), concentration (p-value=0.016; I2=23.68%), and total sperm count (p-value=0.022; I2=13.95%). Spring had better semen quality than summer in terms of concentration (p-value<0.001; I2=33.74%) and percent of normal morphology (p-value<0.001; I2=0%), and also had higher concentration than fall (p-value<0.001; I2=42.82%). Semen analysis in summer had a lower percentage of total motility than those in fall (p-value=0.045; I2=0%). Conclusions Semen parameters follow a seasonal pattern, with winter and spring showing better sperm quality regarding concentration and total sperm count than other seasons. Disclosure No.