Standard recommendations for men before providing a sperm sample for IVF usually suggest abstaining from sexual activity for two to seven days. Millions of couples around the world follow this rule. However, a recent study has challenged these long-standing guidelines, showing that a shorter period of abstinence may significantly increase the chances of achieving a long-awaited pregnancy.

The Impact of Male Factors on IVF Success

Male infertility is one of the main reasons many couples are unable to conceive naturally. In such cases, in vitro fertilization (IVF) is often used, where sperm quality plays a crucial role in the success of the procedure. For decades, semen analysis—assessing sperm concentration, motility, and morphology—has been the standard method for evaluating sperm quality.

Before providing a sperm sample for analysis or for the IVF procedure itself, the World Health Organization (WHO) recommends that men abstain from sexual activity for two to seven days. The idea is that this period allows more sperm to accumulate, theoretically increasing the likelihood of successful fertilization. These recommendations are given both during initial consultations and immediately before egg retrieval.

The Biological Dilemma: Quantity vs. Quality

Behind the apparent simplicity of this rule lies a complex biological dilemma. On one hand, prolonged abstinence does increase the total number of sperm. For example, after up to seven days of abstinence, healthy men can see their sperm count more than double—from 92 to 191 million.

On the other hand, sperm quality declines over time. After maturing, sperm are stored in the tail of the epididymis, and prolonged storage makes them more vulnerable to damage, mainly due to oxidative stress. Cells produce free radicals and are exposed to external toxins, such as polluted air. Sperm are especially sensitive to such damage because of their unique membrane structure and weak repair mechanisms.

Free radicals damage DNA, leading to fragmentation, reduced chances of conception, and a higher risk of miscarriage. Additionally, cell membranes are destroyed, their fluidity decreases, and sperm lose motility, making it harder for them to fuse with the egg.

Thus, the classic WHO recommendation puts doctors and patients in a position to choose: more sperm of lower quality, or fewer but more viable sperm. Until recently, the exact impact of this choice on pregnancy rates remained unclear.

New Research: Shorter Abstinence Means Higher Chances

The world’s first randomized clinical trial dedicated to this dilemma was conducted by a team of Chinese scientists from the First Hospital of Jilin University in Changchun, led by Yang Yu. The results, published in Preprints with The Lancet, could change standard IVF preparation protocols worldwide.

The study involved 453 men undergoing standard IVF procedures. All participants were divided into two groups. The first group (226 men) was instructed to ejaculate about 36 hours before providing the final sperm sample. The second, control group (227 men), followed the standard WHO recommendations of abstaining for two to seven days.

The differences in results were significant. In the group with the shorter abstinence period (36 hours), the pregnancy rate was 46%, compared to 36% in the group following the usual recommendations. Thus, changing just one condition noticeably increased the chances of success. Moreover, miscarriages were less frequent in the short-abstinence group. Although the researchers did not count the number of live births, they suggested that with fewer miscarriages, the number of successful deliveries would also be higher.

Why Does Shorter Abstinence Work?

Scientists have long noted that sperm “deteriorate” if they remain in the body too long without renewal. For example, in 2020, Brazilian researchers compared sperm after one and four days of abstinence and found that with a shorter break, sperm moved better, had less DNA damage, and produced more energy. Frequent ejaculation refreshes the sperm supply and prevents stagnation.

The largest retrospective analysis of more than 23,500 semen samples, published in February 2025, confirmed this pattern and added an important nuance: the effect of abstinence duration varies among men.

If a man initially has good sperm quality, a few days without ejaculation may even be beneficial—there will be more sperm, and their quality will not suffer significantly. However, for men with sperm abnormalities, prolonged abstinence can be harmful: with each passing day, sperm motility steadily declines.

A Personalized Approach Is Key to Success

The same abstinence period is not universal for everyone. What works for a man with normal parameters may worsen the situation for someone with sperm issues. This finding highlights the need for an individualized approach. A short abstinence period may be especially effective for men who already have problems with sperm quality.

It remains an open question whether this effect applies to couples who are not undergoing IVF. The authors of the study plan to investigate this in the future.