Relation between Traditional Semen Parameters, Sperm DNA Fragmentation, and Unexplained Recurrent Miscarriage: A Systematic Review and Meta-analysis

Background: Several studies have explored the relation between traditional semen parameters, sperm DNA fragmentation (SDF), and unexplained recurrent miscarriage (RM), but these findings remain controversial. Hence, we conducted this meta-analysis to explore the relation between traditional semen parameters, SDF, and unexplained RM. Methods: : Multiple databases including PubMed, Google Scholar, MEDLINE, EMBASE, Cochrane Library, Web of Science databases, and China National Knowledge Infrastructure (CNKI) were searched to identify relevant publications. From the eligible publications, data were extracted independently by two researchers. The heterogeneity between publications was calculated using the I 2 statistics and Cochran’s Q test. Statistical analyses were conducted using Stata/SE 12.0 (StataCorp, College Station, Texas, USA). Based on heterogeneity assessment, random- or fixed-effects models were selected to calculate the weighted mean differences (WMDs) and their corresponding 95% confidence intervals (CIs). To estimate the stability of the pooled results, a sensitivity analysis was conducted by excluding each study. To estimate the possible publication bias, Egger’s regression test and Begg’s funnel plot were used. Results: : A total of 280 publications were produced using the search strategy. According to the inclusion/exclusion criteria, 19 publications were eligible. A total of 1182 couples with unexplained RM and 1231 couples without RM were included in this meta-analysis to assess the relation between traditional semen parameters, SDF, and unexplained RM. Our results showed that couples with unexplained RM had significantly increased levels of SDF (WMD=8.77, 95% CI=4.03 to 13.51, P <0.001) and significantly decreased levels of progressive motility (WMD=-4.75, 95% CI=-8.35 to -1.15, P <0.05) and total motility (WMD=-10.30, 95% CI=-15.03 to -5.57, P 0.05), sperm concentration (WMD=-2.28, 95% CI=-4.58 to 0.02, P> 0.05) and total sperm count (WMD=-10.73, 95% CI=-22.11 to 0.66, P >0.05) between couples with and without RM. Conclusion: Couples with unexplained RM had significantly increased levels of SDF and significantly decreased levels of progressive motility and total motility than those of couples without RM. SDF assay may be considered as part of the evaluation of couples with unexplained RM.