Study on the Correlation Between Sperm Mitochondrial Membrane Potential, Seminal Plasma Elastase, Seminal Plasma Zinc, and Pregnancy Outcomes of In Vitro Fertilization-Embryo Transfer in Male Infertility Patients

Aims/Background: Male infertility accounts for 30%–50% of infertility cases. Sperm mitochondrial membrane potential (MMP) and seminal plasma zinc are crucial for sperm motility and function, while seminal elastase reflects infection and inflammation of the reproductive system. This study aimed to explore the roles of sperm MMP, seminal plasma elastase, and seminal plasma zinc in the outcomes of in vitro fertilization-embryo transfer (IVF-ET) among male infertility patients. Methods: Clinical data from 179 male infertility patients who visited the hospital between November 2022 and July 2023 were retrospectively analysed. Of these, 85 cases underwent fresh embryo transfer (ET) after in vitro fertilization (IVF). According to the pregnancy outcomes, the 85 ET cycles were divided into a pregnancy group (n = 42) and a non-pregnancy group (n = 43). Sperm MMP, seminal plasma elastase, and seminal plasma zinc levels were measured. Spearman correlation analysis was used to assess the correlation between fertilization rate and sperm MMP, seminal plasma elastase, and seminal plasma zinc. Binary logistic regression was performed to identify independent factors influencing pregnancy outcomes. Receiver operating characteristic (ROC) curves were constructed to predict diagnostic values of these factors for pregnancy outcomes. Results: The fertilization rate of IVF was positively correlated with sperm MMP (r = 0.362) and seminal plasma zinc (r = 0.415), and negatively correlated with seminal plasma elastase (r = –0.379) (all p < 0.001). Among the 85 ET cycles, the clinical pregnancy rate and live birth rate were 49.41% (42/85) and 41.18% (35/85), respectively. Compared to the non-pregnancy group, the pregnancy group had significantly higher sperm MMP and seminal plasma zinc levels (p < 0.001 and p = 0.009, respectively), and lower seminal plasma elastase levels (p = 0.002). Multivariate analysis identified sperm non-progressive motility (p = 0.013, odds ratio [OR] = 0.478, 95% confidence interval [CI] = 0.267–0.856), sperm MMP (p < 0.001, OR = 1.114, 95% CI = 1.047–1.184), seminal plasma elastase (p = 0.006, OR = 0.996, 95% CI = 0.993–0.999), and seminal plasma zinc (p = 0.024, OR = 1.188, 95% CI = 1.023–1.381) as independent factors affecting pregnancy outcome. ROC analysis showed that sperm MMP (area under the curve [AUC] = 0.748, 95% CI = 0.644–0.851, p < 0.001), seminal plasma elastase (AUC = 0.698, 95% CI = 0.587–0.809, p < 0.001), seminal plasma zinc (AUC = 0.664, 95% CI = 0.549–0.779, p = 0.005), and the combined indicators (AUC = 0.832, 95% CI = 0.747–0.916, p < 0.001) had good predictive values for pregnancy outcomes. Conclusion: Sperm MMP, seminal plasma elastase, and seminal plasma zinc are significantly correlated with fertilization rates in IVF. Combined detection of these three indicators provides strong predictive value for pregnancy outcomes in IVF-ET among male infertility patients.