Effect of sperm DNA fragmentation on the cumulative live birth rate in patients undergoing in vitro fertilization/intracytoplasmic sperm injection treatment

Background: Sperm DNA fragmentation testing is a valuable tool for predicting male infertility independent of routine semen analysis. However, it remains unclear whether sperm DNA fragmentation affects in vitro fertilization/intracytoplasmic sperm injection outcomes, especially their live birth rates. This study aimed to investigate the effects of sperm DNA fragmentation on the cumulative live birth rates over 1 year of in vitro fertilization/intracytoplasmic sperm injection treatment. Methods: This retrospective study included 5050 couples who had undergone in vitro fertilization/intracytoplasmic sperm injection treatment from 2016 to 2022. These patients were divided into four groups according to their sperm DNA fragmentation percentages (group 1: sperm DNA fragmentation <= 10%, group 2: > 10% to <= 20%, group3: > 20% to <= 30%, and group 4: > 30%) determined using the sperm chromatin dispersion assay. Both conservative and optimistic methods were used for estimating cumulative live birth rates, the primary outcome, was defined as an ongoing pregnancy leading to live birth that had arisen from all embryo transfers performed within 1 year following the first ovum pick-up. Results: The conservative and optimistic cumulative live birth rates showed no significant differences between sperm DNA fragmentation groups when total patients or in vitro fertilization patients were analyzed while adjusting for the confounders. However, compared with those in the group with low sperm DNA fragmentation values (<= 10%), the conservative cumulative live birth rate was significantly decreased in intracytoplasmic sperm injection patients in the group with sperm DNA fragmentation > 30%, and the optimistic cumulative live birth rates were significantly decreased in intracytoplasmic sperm injection patients in the three groups with high sperm DNA fragmentation values (> 10% to <= 20%, > 20% to <= 30%, > 30%). These results were further confirmed by the analyses of smooth curves generated by generalized additive models. In intracytoplasmic sperm injection patients, the cumulative live birth rates decreased significantly as the sperm DNA fragmentation increased (p = 0.034), and these effects were stronger with the increase in female age. A similar pattern of correlation between sperm DNA fragmentation and cumulative live birth rate was found in in vitro fertilization patients, but the correlation was not significant (p = 0.232). Discussion and conclusion: Sperm DNA fragmentation has a significant effect on the cumulative probability of achieving a live birth during 1 year of treatment involving intracytoplasmic sperm injection.