Table 4_Quantifying the exposure-response relationship between temperature exposure and semen quality.pdf

BackgroundHigh temperature exposure impacts semen quality, but the exposure-response relationship needs further study.
ObjectivesQuantify the correlations and nonlinear relationships between apparent temperature (AT) exposure and semen quality parameters.
MethodsA total of 5,114 individuals were enlisted as participants from a reproductive medicine center in Wenzhou, a developed coastal cities in eastern China. Multivariate linear regression models were used to quantify the correlations between AT exposure and semen quality parameters. Restricted cubic spline (RCS) and piecewise regression were employed to validate the nonlinear and threshold effects of the exposure-response relationships.
ResultsEach 1 °C rise in AT corresponded to considerable declines in progressive motility (−2.1165; 95% CI: −2.6219, −1.6111) and total motility (−4.8823; 95% CI: −6.2494, −3.5151). AT negatively influenced sperm motility during lag periods of 15–69 and 70–90 days (p < 0.05). Nonlinear RCS analysis detected an inverse U-shaped association between AT and sperm motility, especially at lags 10–14 days (nonlinear p < 0.05). The AT range associated with optimal semen quality parameters was approximately 17.57–22.69 °C based on segmented analysis.
ConclusionsElevated exposure to apparent temperature in the 90 days prior to donation was associated with reduced semen quality. Avoiding excessive temperature exposure, particularly within a 2-week pre-ejaculation window, helps to maintain ideal semen quality.

研究背景：高温暴露可损害精液质量，但二者的暴露-反应关联仍有待进一步研究。
研究目的：量化表观温度（apparent temperature，AT）暴露与精液质量参数之间的相关性及非线性关联。
研究方法：本研究从中国东部沿海发达城市温州的一家生殖医学中心招募了5114名参与者。采用多元线性回归模型分析表观温度暴露与精液质量参数的相关性；通过限制性立方样条（restricted cubic spline，RCS）与分段回归验证暴露-反应关系的非线性与阈值效应。
研究结果：表观温度每升高1℃，精子前向运动率（−2.1165；95%置信区间：−2.6219, −1.6111）与总运动率（−4.8823；95%置信区间：−6.2494, −3.5151）均出现显著下降。在15~69天及70~90天的滞后周期内，表观温度对精子运动能力存在负向影响（P<0.05）。非线性限制性立方样条分析显示，表观温度与精子运动能力呈倒U型关联，尤其在10~14天的滞后周期中（非线性检验P<0.05）。基于分段分析，与最优精液质量参数对应的表观温度范围约为17.57~22.69℃。
研究结论：捐精前90天内的高表观温度暴露与精液质量降低显著相关。避免过度高温暴露，尤其是排精前2周的窗口期，有助于维持理想的精液质量。