背景:在过去的几十年中,精子质量在全球范围内下降。受到影响,其中,根据季节和热量。这项研究旨在通过使用灵活的多变量模型评估其形状并基于无监督分析识别温度变化的不同时间动态模式来解决环境温度与精子质量之间的关联。
方法:进行了一项基于人群的回顾性研究,包括2016-2022年期间在单个医疗中心参加生育和体外受精单元的所有男性样本。灵活的广义模型被拟合来表征精子质量和温度之间的关系,同时考虑患者的特征,并确定与最佳精子质量相对应的温度水平。然后将该信息用于在指定的时间窗口估计调整后的斜率系数。
结果:总计,由3229个个体提供4555个精子样本。精子浓度,运动性和渐进运动性提高了8%,11%和16%,分别,在春季和秋季。此外,它们在早期精子发生过程中的质量随着温度的提高而提高,直到大约23°C-24°C的某个最佳值。在发育阶段后期温度升高与较低的精子浓度和较高的运动性有关。经过一段时间的逐渐变暖,精子浓度和运动性最高。活力较高,精子浓度较低,经过一段时间的热浪或夏天。
结论:本研究通过考虑平均温度和时间动态温度来评估温度在精子生产质量中的作用。它确定了几种温度随时间的变化模式,并对其进行了分层分析。解决了精子发生阶段之间关系的差异。几种机制可以解释所发现的关联,包括热诱导的精子细胞凋亡,并通过过度产生活性氧来破坏精子细胞DNA的完整性。逐渐的全球变暖需要探索个体对室外温度的反应与遗传易感性的关系,生活方式,和其他健康特征。
BACKGROUND: Sperm quality has decreased over the last decades worldwide. It is affected, among others, by season and heat. This study aimed to address the association between ambient temperature and sperm quality by assessing its shape using flexible multivariate models and identifying distinct time-dynamic patterns of temperature change based on unsupervised analysis.
METHODS: A retrospective population-based study has been conducted, including all samples of males attending the Fertility and In-Vitro-Fertilization unit at a single medical center during 2016-2022. Flexible generalized models were fitted to characterize the relations between sperm quality and temperature while accounting for patients characteristics, and to identify temperature levels that correspond with the optimal sperm quality. This information was then used to estimate adjusted slope coefficients at specified time-windows.
RESULTS: In total, 4555 sperm samples were provided by 3229 individuals. Sperm concentration, motility and progressive motility were higher by 8 %, 11 % and 16 %, respectively, during the spring versus the fall season. Furthermore, their quality during early spermatogenesis improved with temperature, until a certain optimum around 23 °C-24 °C. Increasing temperature at later developmental stages was associated with lower sperm concentration and higher motility. Sperm concentration and motility were highest following a period of moderate gradual warming. Motility was higher and sperm concentration was lower, following a period with heatwaves or summer.
CONCLUSIONS: This study assessed temperature role in sperm production quality by considering both average and time-dynamic temperatures. It identified several temperature change patterns over time and stratified the analysis by them. The differences in the relations across stages of spermatogenesis were addressed. Several mechanisms may explain the associations found, including heat-induced apoptosis of the sperm cells, and destruction of sperm cells DNA integrity by over-production of reactive oxygen species. The gradual global warming necessitates exploration of individual response to outdoor temperature in relations to genetic predisposition, lifestyle, and other health characteristics.