Modified strict sperm morphology threshold aids in the clinical selection of conventional fertilization (IVF) or intracytoplasmic sperm injection (ICSI).

For infertility treatment, the selection of in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) is decided by multiplying indicators (including fallopian tube factors, semen count, and semen motility), except for sperm morphology. In this study, we conducted a retrospective analysis, from implantation to birth, over a period of 5 years. A total of 1873 couples with primary or secondary fallopian tube factors and an increased defective sperm morphology rate (DSMR) were divided into different groups to receive IVF or ICSI cycles. By comparing the outcomes, we found that the F1 group (DSMR <96%, IVF group 1) had higher cleavage rate, biochemical pregnancy rate, clinical pregnancy rate, and live birth rate than the F3 group (DSMR >98%, IVF group 3; P < 0.05). In contrast, there was no significant difference in the ICSI subgroups. Furthermore, a comparison of the outcomes between IVF and ICSI showed that the S3 group (DSMR >98%, ICSI group 3) had higher cleavage rate (P < 0.001), biochemical pregnancy rate (P < 0.05), clinical pregnancy rate (P < 0.05) and live birth rate (P < 0.05) than the F3 group. However, the ICSI subgroup had a lower two pronuclei fertilization rate than the IVF subgroup (P < 0.05). Our data suggest that the sperm morphology should also be considered when selecting IVF or ICSI combined with other semen parameters before the first assisted reproductive technologies (ART) cycle, especially for males with severe sperm defects.