Overview
- An Oxford-led meta-analysis in Proceedings of the Royal Society B pooled 115 human studies covering 54,889 men and 56 studies across 30 non-human species.
- Across the data, longer abstinence was linked to more DNA and oxidative damage in human sperm and to lower motility and viability.
- Researchers point to biology that makes mature sperm vulnerable, including limited repair capacity and energy stores that leave cells exposed to reactive oxygen molecules.
- In many species, sperm stored inside females stayed healthier for longer, likely due to specialized storage organs that bathe sperm in antioxidant and nutrient-rich fluids.
- The results challenge the WHO’s 2–7 day abstinence window and align with a December 2025 Chinese IVF trial that reported higher success when men ejaculated within 48 hours before providing a sample, prompting calls for targeted clinical trials to update protocols.