Men trying to conceive may benefit from ejaculating more frequently than current recommendations suggest, according to a major new study that found prolonged sperm storage can reduce sperm quality and increase DNA damage.
The research, led by scientists at the University of Oxford and published in the Proceedings of the Royal Society B, challenges the long-held belief that abstaining from ejaculation for several days before fertility treatment improves reproductive outcomes by increasing sperm count.
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Instead, the findings suggest that while longer abstinence may result in more sperm being available, the sperm themselves may become less healthy the longer they remain stored in the male reproductive tract.
Researchers reviewed 115 human studies involving 54,889 men, alongside 56 studies covering 30 animal species, making it one of the most comprehensive investigations into sperm ageing to date.
Across both humans and animals, the team found consistent evidence that mature sperm deteriorate during storage—a process known as post-meiotic sperm senescence. The decline was associated with increased DNA damage, greater oxidative stress, and poorer sperm movement and survival, all of which can reduce fertility.
The findings suggested that sperm can age independently of the man producing them, with storage time playing a greater role in fertility than previously recognised.
Co-lead author Dr Rebecca Dean of the University of Oxford declared: “Because sperm are highly mobile and have minimal cytoplasm, they quickly exhaust their stored energy reserves and have limited capacity for repair. This makes storage particularly damaging compared to other types of cells.”
She added that regular ejaculation may provide “a small but meaningful boost” to male fertility.
Current guidance from the World Health Organisation recommends up to seven days of sexual abstinence before providing a semen sample for fertility assessment. However, the researchers say their findings raise questions about whether that upper limit is too long.
The study also aligns with more recent evidence suggesting that ejaculating within 48 hours before sperm collection may improve outcomes during in vitro fertilisation (IVF).
While sperm storage occurs naturally in both males and females across many species, the researchers found notable differences in how well sperm survive. Female animals generally maintained sperm quality for longer than males, likely because many species possess specialised sperm-storage organs that nourish and protect sperm with antioxidant-rich reproductive fluids.
Senior author Dr Irem Sepil said understanding these natural mechanisms could inspire new techniques for preserving sperm used in assisted reproduction.
“These specialised storage organs could provide unexplored avenues for biomimicking technology to improve artificial sperm storage in the future,” she said.
Lead author Dr Krish Sanghvi said sperm should be viewed as living populations that undergo ageing, death, and selective survival over time rather than as static cells.
The researchers believe the findings have implications beyond fertility clinics. A better understanding of sperm ageing could also improve captive breeding programmes for endangered species and help scientists understand how different animals evolved strategies to preserve sperm quality.
Despite the findings, the researchers note that sperm count remains an important factor in fertility and that couples experiencing difficulty conceiving should seek personalised medical advice. They also stress that more clinical research is needed to determine the ideal period of abstinence before fertility treatment.
Nevertheless, the study provides some of the strongest evidence yet that when it comes to sperm health, longer storage is not necessarily better, and that timing may matter just as much as quantity.
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