The production of sperm, or spermatogenesis, causes damage to sperm DNA structure, ie. sperm DNA fragmentation. Sperm DNA is further damaged during storage. DNA fragmentation is a normal phenomenon, but increased sperm DNA fragmentation has been shown to cause reduced fertility, miscarriages and certain health issues of the offspring. There are several known causes of increased DNA damage, reactive oxygen species being one of the most important ones. Sperm DNA damage has been linked to aging, obesity, cigarette smoking, varicocele and heat.
Antioxidants, weight loss and other life style modifications have been suggested to improve DNA fragmentation index, but conclusive evidence on the improvement of reproductive outcomes (increased amount of healthy babies born) of these treatment trials is still missing. Therefore routine DNA fragmentation tests are still not recommended. However some couples may benefit from DNA fragmentation testing of the male, for instance in an event of repeated pregnancy loss of several failed fertility treatments.