BACKGROUND

There is considerable uncertainty as to the significance of a high sperm DNA fragmentation index (DFI) for achieving a successful pregnancy.

METHODS

The sperm DFI of 124 patients undergoing 192 IVF cycles and of 96 patients undergoing 155 ICSI cycles was determined using the sperm chromatin structure assay on neat sperm.

RESULTS

The rate of continuing pregnancies in ICSI cycles (but not in IVF cycles) showed significant negative correlation (r = –0.184, P = 0.022) with the DFI value. A threshold value of DFI which showed a significant difference (P = 0.005) in rate of continuing pregnancies between higher and lower DFI levels was found for ICSI cycles to be ≥19%, but no such threshold was found for IVF cycles. However, if the threshold of ≥30% was used for IVF cycles there was a non-significant lowering of the rates of continuing pregnancy and implantation at the higher DFI levels. DFI level had no effect on fertilization rate or on the percentage of embryos having more than 4 cells at Day 3 after fertilization. A high DFI level had a marked significant effect (P = 0.001) on implantation rate in ICSI cycles but not in IVF cycles. A significant positive correlation (r = 0.268, P = 0.001) between DFI and sperm midpiece defects was also noted in the ICSI patients.

CONCLUSIONS

These observations may help to resolve the issues about how, and to what extent, sperm DNA damage impacts upon the success of IVF and ICSI procedures.