Seasons did not significantly affect pregnancy outcomes in infertile patients undergoing IVF-ET.

This retrospective cohort study analyzed data from 1,413 infertile patients undergoing in vitro fertilization-embryo transfer (IVF-ET) at a Reproductive Medicine Center. The investigation compared outcomes across four seasons: spring, summer, autumn, and winter. Primary outcomes included the positive rate of human chorionic gonadotropin (HCG), clinical pregnancy rate, miscarriage rate, and live birth rate. Secondary outcomes encompassed embryo quality, blastocyst formation rate, MII oocyte rate, and available embryo rate.

Analysis revealed no significant differences among the four groups regarding general data, embryo quality, and pregnancy outcomes, with a P value greater than 0.05. Specifically, the season did not significantly affect the positive rate of HCG, clinical pregnancy rate, miscarriage rate, or live birth rate. However, the blastocyst formation rate was significantly higher in spring compared to summer. Additionally, the MII oocyte rate was significantly higher in 2019 than in 2020 and 2022, while the available embryo rate was significantly higher in 2019 than in 2022 and 2023.

Safety and tolerability data were not reported in this study. The study did not report specific adverse events, serious adverse events, discontinuations, or overall tolerability profiles. Key limitations include the retrospective design and the lack of reported absolute numbers or confidence intervals for most comparisons, which restricts the precision of the effect estimates. The study phase and publication type were not reported. These findings suggest that while minor variations exist in specific embryological metrics like blastocyst formation, the overall impact of seasons on critical pregnancy outcomes in IVF-ET appears negligible based on this dataset.