Comparative evaluation of embryological outcomes following conventional IVF and ICSI in couples with unexplained infertility: a single-center prospective study

Objective. To evaluate embryological and clinical outcomes in IVF cycles among couples with unexplained infertility following conventional in vitro fertilization (IVF) versus intracytoplasmic sperm injection (ICSI).

Materials and methods. This single-center prospective comparative study included 116 assisted reproductive technology cycles in couples with unexplained infertility, treated between January 2024 and January 2026. Conventional IVF was performed in 58 cycles and ICSI were performed in 58 cycles each. Cycles with split insemination and those involving preimplantation genetic testing for aneuploidy (PGT-A) were excluded from the analysis. The primary outcome was the normal fertilization rate. The secondary outcomes included the blastulation rate, proportion of good-quality blastocysts, implantation rate, pregnancy rate, and clinical pregnancy rate. To account for potential confounding, adjusted analyses were performed using generalized linear models, and pregnancy rates were compared using Fisher's exact test.

Results. Baseline clinical characteristics were generally comparable between the groups, although the starting gonadotropin dose was higher in the ICSI group. Sperm concentration, total motility, and proportion of mature oocytes were higher in the conventional IVF group. No statistically significant between-group differences were observed in the primary outcome, the normal fertilization rate. Likewise, no significant differences were found in the blastulation rate or the proportion of high-quality blastocysts. Implantation, pregnancy, and clinical pregnancy rates were numerically higher in the ICSI group; however, these differences were not statistically significant. After multivariable adjustment, ICSI was not associated with an increased normal fertilization rate (adjusted odds ratio [aOR] 0.96; 95% confidence interval [CI] 0.74–1.25; p=0.763), blastulation rate (aOR 0.77; 95% Cl 0.59–1.01; p=0.063), good-quality blastocyst formation (aOR 0.80; 95% Cl 0.49–1.31; p=0.370), or implantation rate (aOR 1.01; 95% CI 0.003–330; p=0.962).

Conclusion. In patients with unexplained infertility, ICSI was not associated with improved normal fertilization rates or most embryological outcomes compared with conventional IVF. These findings do not support the routine use of ICSI in couples with unexplained infertility and suggest that a selective approach to choosing a fertilization method is warranted.