Study on the association between night shift work and reproductive functions among male workers: a systematic review and meta-analysis

BackgroundThere has been growing interest to study impact of night shift work on male reproductive health, which is regulated by the hypothalamic-pituitary-gonadal axis and influenced by circadian rhythms. This systematic review and meta-analysis aim to explore the association between night shift work and male reproductive health outcomes.MethodsThis systematic review and meta-analysis followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines (PROSPERO: CRD42022379770). Studies comparing male reproductive parameters [e.g., semen profile, testosterone, follicle stimulating hormone (FSH), luteinizing hormone (LH)] between night shift workers and non-shift workers were systematically searched in PubMed, Scopus and EMBASE databases. Heterogeneity (I2 and Cochran-Q test), risk of bias (Newcastle-Ottawa Scale and funnel plots), sensitivity analyses were performed when applicable.ResultsEight studies were included in this review from 6397 citations screened. The pooled mean difference in sperm count was -18.38 x 106 sperm (-59.82 to 23.07; n = 3, I2 = 85.12%) and serum testosterone was 15 ng/dL (-19.3 to 49.39; n = 5, I2 = 63%), indicating that shift workers had lower sperm counts but marginally higher serum testosterone levels compared to controls. The majority of included studies exhibited a high risk of bias in participant selection, group comparability and exposure assessment.ConclusionThe analysis highlights the potential impact of night shift work on sperm parameters and hormone levels. Future research with standardized methods and larger samples is needed to better understand the circadian disruption's effects, informing healthcare practices and policies for male reproductive health.