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The findings are based on a major, cross-species analysis which revealed a shared pattern across many animals, from insects to mammals. Sperm that is stored (whether in males or females) deteriorates rapidly – resulting in reduced sperm performance, fertilisation success, and embryo quality. Crucially, the new study also offers insights into why this happens.
The researchers carried out a meta-analysis of 115 human studies (involving 54,889 men) and 56 studies across 30 non-human species. This confirmed that mature sperm in storage generally deteriorates in quality independently of the age of the male – a process called post-meiotic sperm senescence.
In humans, longer periods of sexual abstinence were associated with increased sperm DNA damage and oxidative stress, along with reduced sperm motility and viability.