The association between ambient temperature and sperm quality in Wuhan, China

Table 3 Associations between mean temperature and sperm quality at five exposure windows

Lag (days)	Sperm concentration (mln/ml)		Percentage of normal sperm morphology (%)		Progressive motility (%)
Lag (days)	β (95% CI) value	P value	β (95% CI) value	P value	β (95% CI) value	P value
0–9
≤ Threshold	− 0.365(− 0.967,0.238)	0.236	0.750(0.432,1.067)	< 0.001	−0.113(− 0.420,0.195)	0.472
> Threshold	− 0.365(− 0.967,0.238)	0.236	−2.038(−2.783,-1.292)	< 0.001	−0.507(−1.132,0.118)	0.112
10–14
≤ Threshold	1.204(−0.291,2.699)	0.114	0.695(0.413,0.977)	< 0.001	0.299(−0.109,0.706)	0.151
> Threshold	−0.018(− 0.893,0.829)	0.965	− 1.814(− 2.411,-1.217)	< 0.001	− 0.176(− 0.483,0.130)	0.259
15–69
≤ Threshold	0.415(− 0.358,1.187)	0.293	1.896(1.409,2.383)	< 0.001	0.407(0.046,0.767)	0.027
> Threshold	−0.589(−2.694,1.517)	0.584	−1.458(− 1.777,-1.138)	< 0.001	− 0.268(− 0.582,0.046)	0.094
70–90
≤ Threshold	0.480(− 0.375,1.335)	0.271	1.891(1.252,2.530)	< 0.001	0.532(0.236,0.828)	< 0.001
> Threshold	−5.953(−10.126,-1.781)	0.005	−0.934(− 1.251,-0.617)	< 0.001	−2.019(−3.232,-0.807)	0.001
0–90
≤ Threshold	−0.076(−1.002,0.850)	0.872	2.726(2.070,3.381)	< 0.001	0.193(−0.131,0.517)	0.242
> Threshold	−1.445(−3.676,0.785)	0.204	−1.604(− 1.951,-1.258)	< 0.001	− 0.323(− 0.676,0.030)	0.073

The regression coefficients and 95% confidence intervals (CIs) were estimated using a generalized linear model for the relationship between mean temperature and sperm quality, adjusted for body mass index (BMI), education level, smoking status, season of semen sample, days abstaining, and relative humidity. The regression coefficients show changes in sperm quality with a 1 °C increase in mean temperature
0–9, 10–14, 15–69, 70–90, and 0–90 represent the five exposure windows (0–9, 10–14, 15–69, 70–90, and 0–90 days before semen examination, respectively)
≤ Threshold, > Threshold: the study population was divided into ≤ Threshold and > Threshold groups by threshold values of temperature on sperm quality. The threshold values of temperature were 12.88 °C, 21.75 °C, 21.09 °C and 21.89 °C at lag 10–14, lag 15–69, lag 70–90, and lag 0–90 days for sperm concentration; 22.61 °C, 21.72 °C, 14.45 °C, 12.68 °C, and 14.69 °C for the percentage of normal sperm morphology, and 20.94 °C, 15.24 °C, 15.20 °C, 20.81 °C and 17.15 °C at lag 0–9, lag 10–14, lag 15–69, lag 70–90, and lag 0–90 days for progressive motility

ISSN: 1476-069X