Michael Gwarisa
New research from Oxford University suggests that ejaculation frequency may play a key role in maintaining sperm quality, with findings showing that prolonged sperm storage in the body can lead to deterioration over time.
The study found that the longer sperm are stored before ejaculation, the lower their quality, a finding that could have important implications for men trying to conceive naturally or through assisted reproductive technologies such as in vitro fertilisation.
According to the research, extended periods of sexual abstinence in men are associated with increased oxidative stress and DNA damage in sperm. This in turn reduces sperm viability and motility, two critical factors for successful fertilisation.
The findings are based on a large meta analysis that examined 453 effect sizes from 115 studies involving at least 54,889 men across 31 countries. Researchers also analysed 235 effect sizes from 56 studies covering 30 non human animal species to better understand how sperm storage affects reproductive outcomes across the animal kingdom.
The results consistently showed that sperm storage has a negative impact on sperm performance. In men, sperm motility and viability declined with longer storage periods, while markers of cellular damage such as oxidative stress increased.
In non human animals, the pattern was similar. Sperm storage in both males and females reduced fertilisation success and embryo quality, pointing to broader biological consequences beyond humans.
Researchers say this decline is linked to a process known as post meiotic sperm senescence, where sperm deteriorate over time after they are produced. Unlike other cells in the body, mature sperm have limited capacity to repair damage, making them particularly vulnerable during storage.
“Sperm are highly specialised cells with very little capacity for repair,” the study notes, adding that their high metabolic activity and limited energy reserves make them prone to damage over time.
Interestingly, the research also highlights a possible adaptive function of ejaculation. In some species, males have evolved mechanisms to discard older sperm, including behaviours such as masturbation, which may help remove ageing or damaged sperm and make way for newer, healthier cells.
This could explain why more frequent ejaculation is sometimes linked to improved sperm quality, as it reduces the time sperm spend stored in the reproductive tract.
However, the study found that the relationship is not entirely straightforward. While longer abstinence periods may increase sperm count, they can also reduce overall sperm quality. This creates a trade off between quantity and quality, which is particularly relevant in fertility treatment settings.
For example, current guidelines often recommend a period of sexual abstinence before sperm collection for procedures such as IVF. But the new findings suggest that shorter abstinence periods may be more beneficial when the goal is to obtain high quality sperm, especially in procedures like intracytoplasmic sperm injection where only a single sperm is needed.
The researchers also noted that methodological differences in studies, such as how sperm samples are collected, can influence results. Studies that tracked the same individuals over time found stronger negative effects of sperm storage compared to those that compared different groups of men.
Despite the overall negative trend, not all sperm traits were equally affected. While motility and viability declined significantly, factors such as sperm morphology and fertilisation rates showed less consistent changes.
The study found no strong evidence that health status or the exact duration of abstinence significantly altered the overall pattern, suggesting that the ageing process of stored sperm is a general biological phenomenon.
Beyond human fertility, the findings also have implications for animal breeding and conservation programmes, where sperm storage is commonly used. Understanding how storage affects sperm quality could help improve breeding success in captive populations.
Overall, the research highlights the importance of timing when it comes to sperm use and collection. Rather than longer always being better, the study suggests that moderate or shorter storage periods may offer the best balance between sperm quantity and quality.
For men trying to conceive, the message is simple. Regular ejaculation may not just be normal, it could be biologically beneficial.
