This study aimed to investigate whether intracytoplasmic sperm injection (ICSI) shows an advantage over in vitro fertilization (IVF) in non-male factor cycles as the number of oocytes retrieved decreases from four to one. We undertook a retrospective analysis of 1305 IVF/ICSI cycles of non-male factor in which four or fewer oocytes were retrieved. Comparisons were made between conventional IVF (CI) and ICSI when one, two, three or four oocyte(s) were retrieved. Primary outcomes including normal fertilization rate, proportion of embryos per obtained oocyte, cycle cancellation rate, implantation rate, clinical pregnancy rate (PR), live birth rate (LBR), cumulative PR and cumulative LBR were evaluated. The results showed that the normal fertilization rate (72.5% vs. 50.0%) and the proportion of embryos per obtained oocyte (72.5% vs. 55.0%) were significantly increased in one oocyte retrieved cycles in ICSI group as compared with CI group. However, the proportion of embryos per obtained oocyte was markedly decreased in ICSI group when three (52.3% vs. 61.3%) or four (56.9% vs. 64.0%) oocytes were retrieved. The implantation rates, clinical PRs, LBRs, cumulative PRs and cumulative LBRs in CI group were comparable to those in ICSI group when one, two, three or four oocyte(s) were retrieved. In conclusion, ICSI doesn't show advantages over IVF in low oocyte yield cycles of non-male factors, even when only one oocyte was retrieved.
Keywords: cumulative live birth rate; in vitro fertilization; intracytoplasmic sperm injection; low oocyte yield; oocyte number.