DNA damage in prepared semen is negatively associated with semen quality and fertilisation rate in assisted reproduction technology (ART) treatment.

Sperm DNA contains strand breaks and base damage that can potentially affect reproductive health. This study aims to determine to what extent sperm DNA integrity and alkylation is associated with semen quality and assisted reproduction technology (ART) treatment outcomes, in particular fertilisation and cleavage rates. Male partners of couples attending for infertility treatment were recruited. DNA integrity (% tail DNA, sperm with either low (LDD) or high (HDD) damage levels) was measured by a neutral Comet assay and N7-methyldeoxyguanosine (N7-MedG) DNA levels by an immunoslotblot in sperm prepared by density gradient centrifugation. Associations between DNA damage, semen quality and ART treatment outcomes were assessed. N7-MedG levels were lower and the proportion of LDD sperm higher in prepared than in neat sperm samples. The proportion of HDD sperm and % tail DNA were significantly negatively associated and the proportion of LDD sperm positively associated with semen quality. Fertilisation, but not cleavage, rate nor live birth, was significantly negatively associated with N7-MedG levels, the proportion of HDD sperm and % tail DNA and was positively associated with the proportion of LDD sperm. These results confirm that DNA damage, even in prepared sperm, is associated with adverse semen quality and suggest that sperm DNA damage affects the early stages of embryo formation.