P-527 Low sperm motility and elevated sperm DNA fragmentation index (DFI) are associated with increased rates of embryo aneuploidy in patients with advanced reproductive age
Authors: Abramov R , Madjunkov M , Moskovtsev S , Librach C , Madjunkova S 
Published: July 2024

Abstract

Study question
Is there a correlation between the paternal age, sperm characteristics, and the prevalence of chromosomal abnormalities in embryos generated through in vitro fertilization (IVF)?

Summary answer
A correlation exists between advanced paternal age, suboptimal sperm parameters, and elevated rates of embryo aneuploidy in individuals of advanced reproductive age.

What is known already
The exact mechanisms underlying the relationship between paternal age, sperm quality and embryo ploidy, although a subject of considerable research in assisted reproduction, are not fully elucidated. Some reports, including our group’s, suggest that paternal age may influence sperm quality and segmental embryo aneuploidy, while others suggest a potential association between high DFI(DNA Fragmentation Index) and an increased likelihood of embryo aneuploidy. Studies also show that sperm with optimal motility and fertilization competence are more likely to contribute to the development of euploid embryos, while data on the effect of abnormal sperm parameters on embryo ploidy is scarce and conflicting.

Study design, size, duration
This was a retrospective cohort study performed in the Reproductive Genetics Department, CReATe Fertility Centre, Toronto, Canada, between January 2019-December 2023. A total of 7628 blastocysts from 1512 cycles (1392 patients) were analyzed using high resolution NGS PGT-A. Sperm motility, concentration and DFI data, as well as, IVF cycle parameter data were collected. In addition, age of gamete providers and any relevant clinical, laboratory and demographic data were obtained for statistical analysis.

Participants/materials, setting, methods
Embryos were allocated into two groups by oocyte-provider age: OP-≤33 years and OP-≥34 years. Each group was divided into two sub-groups by paternal age: SP-≤39 years (n = 4570); SP-≥40 years (n = 3058). Multiple logistic/ordinal regressions were conducted to evaluate Segmental abnormalities and Segmental mosaicism between these age groups in relation to sperm DFI (GOOD ≤15%; FAIR 15-30%; POOR ≥30%), Motility (HIGH &gt;40%; LOW &lt;40%) and Count (LOW &lt;5 mil/ml; MEDIUM 5-15 mil/ml; HIGH &gt;15 mil/ml).

Main results and the role of chance
PGT-A analysis of 7628 embryos showed 51.5% euploidy, 36.7% aneuploidy and 11.8% mosaicism. In the OP-≤33 group, there were no significant differences between the two paternal age groups for euploidy, aneuploidy or mosaicism rates. In the OP-≥34 group, decreasing euploidy rates (p &lt; 0.0001 and increasing aneuploidy rates (p &lt; 0.0001) were observed between the two paternal age groups, while mosaicism rates were not different, an expected oocyte age-effect result. No significant differences in aneuploidy rates were observed for each of the sperm parameters (DFI, motility, count) in the groups of the OP-≤33 with SP-≤39, OP-≤33 with SP-≥40 and OP-≥34 with SP-≤39. In the group of OP-≥34 with SP-≥40, in patients with LOW motility vs. HIGH motility the aneuploidy rates were higher (56.8% vs.50.6%, p = 0.005) and euploidy rates were lower (33.8% vs.38.4%, p = 0.03). Each sperm parameter in each age group was further analyzed for chromosomal segmental abnormalities and segmental mosaicism. Higher rates of segmental abnormalities were seen in LOW motility groups with POOR-DFI compared to GOOD DFI in OP-≤33 with SP-≤39 (3.2% vs. 7.4%, p = 0.03).

Limitations, reasons for caution
The main limitation was the retrospective nature of this study; however, multiple regression analyses were conducted to limit potential bias by adjusting for sperm and oocyte characteristics. In addition, PGT-A analysis cannot provide information on origin of the aneuploidy and all conclusions are deduced from indirect associations to paternal age.

Wider implications of the findings
The identified associations could stimulate further research into exploring the molecular/cellular processes involved in fertilization, early embryonic development, and the potential impact of sperm-related factors on the chromosomal stability of developing embryos. The broader implications of these findings extend to clinical practice, patient counseling, technological advancements, and ethical considerations.

Trial registration number
not applicable