Scientists from the First Hospital of Jilin University in Changchun (China) have found that a short period of abstinence before providing a semen sample for in vitro fertilization (IVF) increases the likelihood of pregnancy by about 10%. The study results were published in The Lancet.

The researchers focused on one of the key challenges of IVF—the low predictability of procedural success—against the backdrop of a global decline in sperm quality over the past 50–70 years, which has forced more couples to turn to assisted reproductive technologies. This issue is especially important for women of advanced reproductive age, for whom IVF effectiveness can drop to as low as 16%.

Nearly 500 men took part in the study. One group was advised to ejaculate 48 hours before providing a semen sample, while the other followed standard recommendations and abstained from ejaculation for two to seven days. The researchers then compared IVF outcomes in the participants’ female partners.

The analysis showed that a shorter abstinence period was associated with significantly better outcomes. The clinical pregnancy rate—confirmed by ultrasound with the presence of a gestational sac and fetal heartbeat—was 54.4% in the 48-hour group versus 44.9% in the control group. The ongoing pregnancy rate was also higher: 46% compared with 36%.

The authors emphasize that this is the first prospective randomized controlled trial specifically designed to assess the impact of abstinence duration on IVF outcomes. In their view, using a so-called “trigger day”—ejaculation 48 hours before semen collection—could become a simple and accessible way to improve the effectiveness of the procedure without additional medical interventions.

The researchers note that the data do not reflect live birth rates; however, even at the stages of clinical and ongoing pregnancy, the effect appears statistically and practically significant.

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