Effect of fertilization by intracytoplasmic sperm injection versus conventional insemination on embryo cleavage rates.

PURPOSE: To determine if fertilization by conventional oocyte insemination vs intracytoplasmic sperm injection (ICSI) causes any difference in the maximum number of blastomeres of fresh or frozen thawed embryos transferred. METHODS: Retrospective evaluation of all in vitro fertilization (IVF) cycles over a 10-year period in cycles having a 2 embryos transferred where the semen analysis was normal except for strict morphology which was allowed to be 2-5% normal. The percentage of the maximum number of blastomeres in any transfers was compared according to the method of insemination. RESULTS: There were no differences in the maximum blastomere numbers in cycles where there was conventional insemination vs ICSI. CONCLUSIONS: Though higher pregnancy rates have been found following the transfer of embryos derived from conventional oocyte insemination vs ICSI, and higher pregnancy rates were found following single embryo day 3 transfers with embryos with more blastomeres, the beneficial effect of conventional insemination does not seem to be related to forming embryos with more rapid cleavage.