Advanced Paternal Age: A New Indicator for the Use of Microfluidic Devices for Sperm DNA Fragmentation Selection.

New social conditions and progress in ART have both contributed to the delay in parenthood in developed countries. While the effects of maternal age have been widely studied, paternal age is poorly understood, and there are no specific guides on ART techniques to treat its deleterious effects. It is known that there is an increase in sperm DNA fragmentation (SDF) in elderly men, and new sperm selection devices using microfluids have been developed. This study analyses 189 ICSI cycles with donor oocytes performed between January 2018 and February 2022. Spermatozoa were selected using an MSS device or density gradients, followed by ICSI fertilization and fresh/thawed embryo transfer. We assessed the association between the selection technique, paternal age (< or ≥45) and reproductive outcomes. Fertilization (FR), blastulation (BR), implantation (IR), live-birth (LBR) and miscarriage (MR) rates were calculated. The results showed significantly higher IR (57.7% vs. 42.5%) and LBR (42.9% vs. 30.3%) when applying MSS selection, and particularly higher BR, IR and LBR when the paternal age was equal to or over 45 years (BR: 64.4 ± 23% vs. 50.1 ± 25%, IR: 51.5% vs. 31.6% and LBR: 42.4% vs. 23.7%). We also found a negative correlation between BR and paternal age (r2 = 0.084). The findings show that MSS enhances success in assisted reproduction cycles with ICSI, especially in couples with advanced paternal age. We propose advanced paternal age as a new indicator for the application of sperm selection techniques that reduce fragmentation.