Human Sperm Cryopreservation as an Alternative to the Decline of Sperm Quality With Aging

This observational study will evaluate whether sperm cryopreservation can help preserve sperm quality and molecular characteristics that may be affected by increasing paternal age. Men aged 18 years and older will provide a semen sample and a blood sample for laboratory analysis. Each semen sample will be divided into fresh, slow-frozen, and vitrified aliquots. The study will compare sperm quality (as assessed by computer-assisted sperm analysis), DNA methylation profiles, DNA fragmentation, sperm telomere length before and after cryopreservation. The effects of age on these parameters will also be assessed. The impact of age on seminal plasma extracellular vesicle composition and blood cell telomere length will also be analysed. The goal is to determine whether sperm cryopreservation may represent a strategy for preserving sperm characteristics associated with younger paternal age.

Inclusion Criteria: * Male participants aged 18 to 65 years * Attending IVI Murcia for semen analysis and/or assisted reproduction treatment * Able and willing to provide written informed consent * Willing to provide a semen sample and a blood sample for research purposes Exclusion Criteria: * Previous diagnosis of azoospermia or severe oligozoospermia (sperm concentration \