Encouraging men to ejaculate more frequently may improve fertility, as new research shows that sperm quality declines the longer it remains in the body.
The study found that prolonged abstinence is linked to increased DNA damage and oxidative stress in sperm, making them less viable and reducing their ability to swim effectively.
The findings challenge existing practices in fertility clinics, where men are often advised to abstain from ejaculation for several days before providing samples. Researchers suggest that shorter abstinence periods may produce higher-quality sperm.
“In men, the negative effects we found on sperm DNA damage and oxidative damage were large-ish, so we are confident that this is a biologically meaningful and important effect,” said Dr Krish Sanghvi, a biologist at the University of Oxford and lead author on the study.
The conclusions are based on a meta-analysis of 115 human studies involving nearly 55,000 men, alongside 56 studies on 30 non-human species. Across both humans and animals, sperm quality consistently declined during storage in the male body, regardless of age.
Current guidelines from the World Health Organization recommend abstaining from ejaculation for two to seven days before fertility tests or IVF procedures. However, the study notes that these recommendations prioritise sperm count rather than sperm quality.
Researchers now say that approach may need to change. “All we recommend is that clinicians and couples reconsider whether long abstinence is always good, because abstinence leads to deterioration in sperm quality,” Sanghvi said.
“If sperm quantity is the only thing that matters for a clinic or couple, then sexual abstinence is not necessarily a bad thing,” Sanghvi said. “But usually fertilisation success will be determined not only by how many sperm there are but the quality of the sperm too, for example in IVF.”
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Although the Oxford study did not find a direct link between abstinence duration and fertilisation rates in humans, other evidence points to a connection.
A recent clinical trial involving 453 couples compared pregnancy outcomes based on abstinence periods before IVF. Men who abstained for less than two days recorded a pregnancy rate of 46 per cent, while those who abstained for between two and seven days had a lower rate of 36 per cent.
For couples trying to conceive naturally, researchers say moderation may be key. Long periods without ejaculation may damage sperm, while very frequent ejaculation may reduce sperm count or maturity.
“For couples, our recommendation would be that longer abstinence is not always a good thing, and that a balance between quantity [and] quality needs to be struck,” Sanghvi said.
Experts say the findings align with emerging evidence in reproductive medicine.
Allan Pacey, a professor of andrology at the University of Manchester, said: “There has been growing evidence in recent years that a shorter abstinence time might be beneficial when undergoing assisted reproduction such as IVF. This is because with a short abstinence time the sperm are fresher, more motile and have lower levels of DNA damage.
“The two to seven days abstinence rule is important to stick to for men undergoing semen analysis at the diagnosis stage, as it allows results to be compared over time between laboratories and against international benchmarks. But it isn’t as important when IVF treatment is actually taking place.
“For assisted reproductive technology (Art) treatments, it’s having the freshest, most healthy sperm that is probably more important. We can do IVF treatment with a low number of sperm, and even lower if we do ICSI (intracytoplasmic sperm injection), so it isn’t as necessary for men to save up their sperm in the way that we once thought.”
(The Guardian UK)