Double-stranded sperm DNA damage is a cause of delay in embryo development and can impair implantation rates

Objective: To analyze the effect of single and double stranded sperm DNA fragmentation (ssSDF and dsSDF) on human embryo kinetics monitored under time-lapse system. Design: Observational, double blind, prospective cohort study. Setting: University, University spin-off and private center. Patients: 196 embryos from 43 infertile couples included prospectively. Interventions: None Main outcome Measures: ssSDF and dsSDF were analyzed in the same semen sample used for ICSI. Embryo kinetics was then monitored using time-lapse technology, obtaining timings of each embryo division. Results When comparing embryos obtained from semen samples with low dsSDF and high dsSDF, splitting data using, a statistically significant delay in high dsSDF was observed in 2nd polar body extrusion, T4, T8, morula, and starting blastocyst (p<0.05) and embryo implantation rates were impaired (p=0.037). Embryo kinetics and implantation rates were not significantly affected when high values of ssSDF are present (p>0.05 and p=0.102). Different patterns of delay in embryo kinetics were observed for these different types of DNA damage: dsSDF caused a delay along all stages of embryo development, however, its major effect was observed at 2nd polar body extrusion and morula stages, coinciding with embryo DNA damage checkpoints activation described before; ssSDF caused its major effect at pronucleus stage, but embryo kinetics was then restored at all the following stages. Results show that dsSDF could be the main type of DNA damage present affecting embryo development in ICSI cycles, probably due motility-based sperm selection in this assisted reproduction procedure. Conclusions Double stranded sperm DNA damage caused a delay on embryo development and impaired implantation, while single stranded DNA damage did not significantly affect embryo kinetics and implantation.