There appears to be a threshold of sperm DNA damage (fragmentation) beyond which embryo development and pregnancy are impaired. Fertile men with normal sperm parameters almost uniformly have low levels of DNA breakage, whereas infertile men, especially those with abnormal semen parameters, have increased DNA damage. Moreover, up to 8% of infertile men will have abnormal DNA integrity despite normal semen parameters.
The aetiology of sperm DNA damage, much like male factor infertility, appears to be multifactorial and may be due to intrinsic or external factors. Intrinsic factors include protamine deficiency, mutations that affect DNA compaction, and advanced paternal age. High levels of reactive oxygen species (ROS’) In addition to infertility, men with abnormally high DNA fragmentation are more likely to result in recurrent miscarriages