Mar 26, 2026
3 min read
The need to fast before fertility treatment is being investigated because research shows that sperm degrades while it remains in the body.
Encouraging men to ejaculate more often can boost their fertility, according to researchers who found that sperm degrades over time in the body.
The longer the men were sexually inactive, the more their sperm showed signs of DNA damage and oxidative stress, and the more tests rated their sperm as weak and poor swimmers.
The work has implications for fertility clinics and suggests that if doctors want to collect the highest quality sperm, men probably shouldn't abstain from ejaculating for several days, as the guidelines suggest.
“In men, the negative effects we found on sperm DNA damage and oxidative damage were substantial, so we believe these are significant and important biological effects,” said Dr.Krish Sanghvi, a biologist at Oxford University and lead author of the study.
The findings emerged from a meta-analysis that included 115 human studies involving nearly 55,000 men and 56 studies that looked at the effects of sperm preservation in 30 non-human species.In humans and other animals, spermatozoa tend to deteriorate while remaining preserved in males, regardless of the male's age.
The World Health Organization (WHO) recommends that men refrain from ejaculating for two to seven days before donating sperm for pregnancy tests or IVF.However, the guidelines are designed to obtain the highest sperm count rather than prioritizing the best quality sperm.
That decision may now be more nuanced."All we're suggesting is that doctors and couples reconsider whether long-term abstinence is always good because abstinence reduces sperm quality," Sanghavi said.Details are published in Proceedings of the Royal Society B.
"If the sperm count is the only thing that matters to the health department or men, then it's not a bad thing to leave," said Sangui.
While the Oxford study found no impact of abstinence on fertilisation rates in humans, a recent clinical trial involving 453 couples did reveal a link.
In the experiment, IVF doctors compared pregnancy rates for two groups of couples.The first group of men abstained from ejaculation for less than two days before providing sperm for IVF treatment.A second group of men followed WHO recommendations and abstained for two to seven days before providing sperm.The pregnancy rate was 46% when the men abstained for less than 48 hours and only 36% for those who did not ejaculate longer.
For couples trying to conceive naturally, a period between two and seven days may be reasonable.Avoid too long and the sperm can be damaged and not move as much.Avoid too little and the sperm may not be abundant or mature enough.''to be stable,'' Sanghvi said.
Allan Pacey, professor of andrology at the University of Manchester, said: "In recent years there has been increasing evidence that short-term abstinence can be beneficial in assisted reproduction such as IVF.
"The rule of 2 to 7 days of abstinence is very important for people to respect sperm analysis or ejaculation at the diagnostic stage, as it allows results between laboratories to be compared with international references. But it is not very important when IVF treatment is actually carried out.
"For assisted reproduction (artificial) therapy, it contains the healthiest sperm, which is probably more important. We can do IVF treatment with lower sperm counts and even less if we do ICSI (intracytoplasmic sperm injection), so there is no need for men to save their sperm as we thought."
