Assessment of the effects of subclinical hypothyroidism on male reproductive parameters: a meta-analysis approach

Subclinical hypothyroidism (SCH) is a common endocrine disorder that potentially affects reproductive health. Despite its prevalence, the precise relationship between SCH and sperm quality remains unclear. A comprehensive search was conducted across electronic databases to identify relevant studies exploring the association between SCH and sperm quality parameters, covering literature published from January 2000 to January 2024. The standardized mean difference (SMD) was used to compute pooled effect estimates with 95% confidence intervals ( CI s). Additionally, meta-regression and subgroup analyses were performed to investigate the potential sources of heterogeneity. The meta-analysis included a thorough examination of 10 studies comprising 2239 participants. According to the findings of this meta-analysis, SCH significantly affects sperm quality. Specifically, the study suggests a decrease in the volume of seminal fluids (SMD = −0.186; 95% CI : −0.385 to 0.013; P = 0.067), total sperm count (SMD = −0.604; 95% CI : −1.178 to −0.030; P = 0.039), sperm morphology (SMD = −0.784; 95% CI : −1.405 to −0.162; P = 0.013), and progressive motility (SMD = −1.437; 95% CI : −2.147 to −0.727; P <0.001). However, SCH was also associated with an increase in sperm concentration (SMD = 0.112; 95% CI : −0.058 to 0.281; P = 0.017). Our meta-analysis provides compelling evidence of the adverse effects of SCH on sperm quality parameters. These findings underscore the importance of considering the thyroid function in the assessment and management of male infertility.