A clinical trial suggests that men who ejaculate within 48 hours before providing sperm samples for IVF achieve higher ongoing pregnancy rates than those who abstain longer. The study, involving over 450 men, found a 46% success rate in the shorter abstinence group compared to 36% in the longer one. Experts note potential benefits but call for further research on live births and other factors.
In vitro fertilisation (IVF) outcomes may hinge on the timing of male ejaculation prior to sperm collection, according to the first clinical trial examining abstinence intervals. Conducted by Yang Yu and colleagues at First Hospital of Jilin University in Changchun, China, the study compared two groups of men undergoing conventional IVF.
One group of 226 men was instructed to ejaculate about 36 hours before producing their sample, aligning with the 36-hour window after a woman's trigger injection that matures eggs for collection and fertilisation. The other group of 227 men abstained from 48 hours to seven days beforehand, following standard guidelines that recommend a two-to-seven-day window to balance sperm quality and quantity.
Results showed the shorter abstinence group had a 46% ongoing pregnancy rate, versus 36% for the longer abstinence group. David Miller at the University of Leeds, who was not involved, described the findings as encouraging, though he cautioned that ongoing pregnancies do not fully capture live birth rates. He observed a lower, albeit not statistically significant, miscarriage rate in the shorter group, suggesting potential for more live births.
Longer abstinence exposes sperm to toxins like free oxygen radicals from metabolism and pollution, potentially causing DNA damage and reducing quality, explained Richard Paulson at Keck School of Medicine of USC. Shorter intervals risk lower sperm counts but prior research, including a 2024 meta-analysis, indicated benefits like improved semen quality and motility with less than four days' abstinence.
Paulson highlighted study limitations, such as mixing fresh and frozen embryos, and a puzzling drop in fertilisation rates despite higher ongoing pregnancies in the shorter group. "This type of extraordinary claim would require extraordinary proof, with careful control of all possible factors," he said. Jackson Kirkman-Brown at the University of Birmingham called it a solid proof of shorter abstinence yielding better sperm, with possible implications for non-IVF couples.
The findings were published as a preprint with The Lancet (DOI: 10.2139/ssrn.5821645).
