Overview
- The Oxford-led meta-analysis, published Wednesday in Proceedings of the Royal Society B, combined 115 human studies involving 54,889 men with 56 studies across 30 species.
- In men, longer abstinence correlated with more sperm DNA damage and oxidative stress with lower motility and viability, with stronger effects in studies that followed the same men over time.
- The authors described the overall human effects as modest, and they did not find consistent drops in fertilization or embryo quality in people.
- Across animals, stored sperm more often led to poorer fertilization and embryo outcomes, and females tended to preserve sperm better using antioxidant-rich storage organs.
- The results raise questions about the WHO 2–7 day abstinence window, with evidence that ejaculating within 48 hours may improve some IVF outcomes while ICSI may favor even shorter waits.