Cumulative live birth rates after IVF/ICSI cycles with sperm prepared by density gradient centrifugation vs. swim-up: a retrospective study using a propensity score-matching analysis

Background Density gradient centrifugation (DGC) and swim-up (SU) are the two most widely used sperm preparation methods for in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). However, existing comparisons of IVF/ICSI outcomes following these sperm preparation methods are insufficient and controversial. Methods This retrospective study included all first autologous IVF and ICSI cycles performed between March 1, 2016, and December 31, 2020 in a single university-based center. A total of 3608 cycles were matched between DGC and SU using propensity score (PS) matching for potential confounding factors at a ratio of 1:1. The primary outcome was the cumulative live birth rate (cLBR) per aspiration. Results PS matching provided 719 cycles after DGC and 719 cycles after SU. After adjusting for confounders, the recovery rate, progressive motility rate after sperm preparation, fertilization rate, good-quality embryo rate, and blastocyst formation rate were similar between the DGC and SU groups. The cLBR (odds ratio [OR] = 1.143, 95% confidence interval [CI]: 0.893-1.461) and LBR per transfer (OR = 1.082, 95% CI: 0.896-1.307) were also not significantly different between the groups. Furthermore, no significant differences were found in all of the laboratory and clinical outcomes following conventional IVF or ICSI cycles between the two groups. However, a significantly higher fertilization rate (beta = 0.074, 95% CI: 0.008-0.140) was observed when using poor-quality sperm in the DGC group than in the SU group. Conclusions Sperm preparation using DGC and SU separately resulted in similar IVF/ICSI outcomes. Further studies are warranted to compare the effects of these methods on IVF/ICSI outcomes when using sperm from subgroups of different quality.

Automated summary

This retrospective study compared the effects of density gradient centrifugation (DGC) and swim-up (SU) on the outcomes of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). After matching and adjustment, no significant differences were found between the DGC and SU groups in terms of sperm recovery rate, progressive motility rate, fertilization rate, embryo quality, and blastocyst formation rate. The cumulative live birth rate and live birth rate per transfer were also not significantly different between the groups. However, the DGC group had a significantly higher fertilization rate when using poor-quality sperm compared to the SU group.