Timing May Be Everything: A Study on Sperm Quality Suggests Diminished Period of Abstinence
Recent clinical research from Doctors Da Li and XiuXia Wang of Shenyang Hospital, published in the journal Molecular and Cellular Proteomics, shows both sperm quality and reproductive outcomes are improved when semen is provided after just 1-3 hours of abstinence. The prevailing conventional wisdom in reproductive medicine is that limiting sexual activity between conception efforts can improve chances of pregnancy success. This research involved nearly 500 couples to determine if decreasing abstinence time could change their success rates.
Prior studies from this lab had shown that semen produced shortly after ejaculation (within approximately three hours) had faster and more motile sperm than if abstention had been several days. Uncertain, however, was why the sperm changed and if the changes seen affected fertility.
To understand these questions, semen samples were studied for volume and motility after either several days or after just one to two hours abstention. As had been observed previously, the sperm from short periods of abstinence did not have abnormally low volume and also moved faster.
The protein makeup of the semen samples was then investigated using a laboratory technique called mass spectrometry, and there were significant molecular differences, as well, with the majority of the affected proteins involved in cell adhesion, a function necessary for sperm binding to the egg cell. Other involved proteins in the semen involved those that combatted oxidative stress (reactive oxygen species, ROS). The inference is that the longer sperm exist between ejaculations, the more vulnerable they become to DNA damage by ROS, which could impair their ability to form a viable embryo.
The team also ran a study of the approximately 500 couples undergoing IVF treatment at the Shenyang fertility clinic to determine if there were differences in success rates. Men in the control group provided semen samples after several days of abstinence; however, men in the experimental group had three or fewer hours of abstinence before providing samples. IVF was performed as usual with the two sample types, with the live birth rate in the control group about 30 percent and approximately 40 percent in the experimental (shorter abstinence) group.
Dr. Li plans further research to investigate differences in post-translational protein modifications that his lab saw between the types of semen samples. "This is a very new field," said Li. Indeed, this is a novel area of reproductive research with profound implications for present clinical practice.
Journal Reference: Zi-Qi Shen, Bei Shi, Tian-Ren Wang, Jiao Jiao, Xuejun Shang, Qi-Jun Wu, Yi-Ming Zhou, Tie-Feng Cao, Qiang Du, Xiu-Xia Wang, Da Li. Characterization of the Sperm Proteome and Reproductive Outcomes within VitroFertilization after a Reduction in Male Ejaculatory Abstinence Period. Molecular & Cellular Proteomics, 2018; mcp.RA117.000541 DOI: 10.1074/mcp.RA117.000541