The study, published in Proceedings of the Royal Society B, analysed data from 115 human studies involving nearly 55,000 men, alongside 56 studies covering 30 animal species, including birds, bees, reptiles, and mammals. Researchers examined how sperm storage—either within the male body before ejaculation or within females after mating—affects reproductive outcomes.
Findings from the analysis showed that prolonged abstinence is associated with declines in key indicators of sperm health, including motility (the ability to swim) and viability (the proportion of living sperm), as well as increased DNA damage. These changes suggest that sperm stored for longer periods may be biologically less effective than freshly produced sperm.
The study also found similar patterns across the animal kingdom. Embryos created using stored sperm—whether retained in males or preserved in females—tended to have lower survival rates. Researchers attributed this to biological deterioration that occurs over time in stored sperm cells.
Interestingly, the rate of decline differs between sexes. While sperm quality in females also decreases after mating, it does so more slowly. This is due to protective substances in the female reproductive tract that help preserve sperm for longer periods. In humans, sperm can survive inside the female body for several days, while in some species—such as queen ants, bees, and certain bats—females can store sperm for months or even years before fertilisation.
The findings may have important implications for fertility treatment. The researchers suggest that using freshly ejaculated sperm could improve outcomes in assisted reproductive procedures such as in vitro fertilisation (IVF).
Current guidelines from the World Health Organization recommend abstaining from ejaculation for two to seven days before providing a sperm sample for analysis or treatment. However, the study indicates that shorter abstinence periods might better optimise sperm quality.
Lead author Krish Sanghvi said the results highlight the need to balance sperm quantity with quality.
“Abstinence leads to deterioration in sperm quality,” he noted, adding that while longer periods without ejaculation may increase sperm count, fertilisation success depends on multiple factors, particularly sperm health.
The researchers concluded that both clinicians and couples may need to rethink conventional advice, especially in fertility settings where the quality of sperm plays a decisive role in successful conception.