A new study suggests that prolonged abstinence from sex or masturbation may negatively impact sperm quality in men. The research, published in Proceedings of the Royal Society B: Biological Sciences, analyzed data from 115 human studies involving nearly 55,000 men and 56 studies across 30 non-human species. The findings indicate that sperm stored in the testes deteriorates over time, leading to increased DNA damage, oxidative stress, and reduced motility and viability.
Core Findings
The study found that sperm stored for extended periods—due to abstinence—exhibits higher levels of oxidative stress and DNA damage. This deterioration was observed regardless of the man's age. The researchers noted that sperm cells have limited capacity for repair and energy reserves, making them particularly vulnerable to aging when stored. The findings also suggest that longer abstinence may lower fertilization success rates and embryo quality, though the study did not find consistent evidence of reduced fertilization rates in humans.
Implications for Fertility
The results raise questions about current World Health Organization (WHO) guidelines, which recommend 2 to 7 days of abstinence before semen samples are taken for assisted reproduction. The study suggests that the upper limit of seven days may be too long, potentially affecting sperm quality. The researchers emphasized that while sperm production continues throughout a man's life, individual sperm cells begin to age and accumulate damage once stored.
Scientific Perspective
Co-lead author Dr. Rebecca Dean from the University of Oxford explained that sperm cells are highly mobile and have minimal cytoplasm, making them more susceptible to damage. Lead author Dr. Krish Sanghvi noted that the study highlights how regular ejaculation can provide a small but meaningful boost to male fertility. The researchers also suggested that the body or assisted reproduction techniques may compensate for some sperm damage, though the negative effects on sperm health were still evident.
Animal vs. Human Findings
The study found similar patterns in non-human species, including birds, mice, monkeys, and insects. In animals, longer sperm storage was linked to reduced fertility outcomes, though the human data was less conclusive. The researchers speculated that poor-quality sperm may die more rapidly, preventing fertilization even if DNA damage or motility issues are present.
Conclusion
The findings suggest that regular ejaculation may improve sperm quality and fertility success, particularly for couples undergoing IVF. However, the study does not definitively prove that abstinence directly causes infertility in humans, only that it is associated with poorer sperm health.