Table 3.

Sensitivity analyses of weighted linear regression models

Covariates	TSC		SC		PR		TM
	Regression coefficient (95% CI)	P value	Regression coefficient (95% CI)	P value	Regression coefficient (95% CI)	P value	Regression coefficient (95% CI)	P value
Only cross-sectional studies were included	− 2.85 (− 2.96, − 2.75)	< 0.001	− 0.55 (− 0.62, − 0.48)	< 0.001	− 0.28 (− 0.36, − 0.20)	< 0.001	0.33 (0.32, 0.35)	< 0.001
Removing studies of sperm donors	− 1.10 (− 1.70, − 0.50)	< 0.001	− 0.57 (− 0.67, − 0.46)	< 0.001	− 0.27 (− 0.29, − 0.25)	< 0.001	− 0.36 (− 0.46, − 0.27)	< 0.001
Removing studies not reporting start years and end years	− 2.92 (− 3.10, − 2.74)	< 0.001	− 0.43 (− 0.54, − 0.32)	< 0.001	− 0.19 (− 0.28, − 0.10)	< 0.001	0.43 (0.34, 0.53)	< 0.001
Removing years before 1999	− 3.27 (− 3.66, − 2.88)	< 0.001	− 0.91 (− 0.92, − 0.90)	< 0.001	− 0.25 (− 0.32, − 0.18)	< 0.001	− 0.37 (− 0.43, − 0.30)	< 0.001
Removing studies with poor quality	− 3.00 (− 3.20, − 2.81)	< 0.001	− 0.46 (− 0.51, − 0.41)	< 0.001	− 0.16 (− 0.20, − 0.12)	< 0.001	0.26 (0.21, 0.32)	< 0.001
Removing studies with sample size < 100	− 0.42 (− 0.60, − 0.24)	< 0.001	− 0.27 (− 0.32, − 0.22)	< 0.001	− 0.23 (− 0.28, − 0.17)	< 0.001	− 0.37 (− 0.41, − 0.32)	< 0.001