Table 3 Subgroup meta-analysis of the included studies
Subgroup analysis | No. studies | Test of association | Heterogeneity | ||
|---|---|---|---|---|---|
SMD (95% CI) | Pvalue | Isquare | Pvalue | ||
Study design PM2.5 | |||||
 Cross-sectional | 3 | −0.061 (−0.15, 0.18) | 0.12 | 35.11 | 0.21 |
 Longitudinal study | 5 | −0.254 (−0.15, 0.18) | 0.04 | 98.39 | <001 |
Study design PM10 | |||||
 Cross-sectional | 3 | −0.063 (−0.15, 0.01) | 0.10 | 34.02 | 0.22 |
 Longitudinal study | 4 | −0.237 (−0.48, 0.02) | 0.07 | 98.15 | <001 |
Semen analysis method PM2.5 | |||||
 CASA | 4 | −0.190 (−0.44, 0.04) | 0.11 | 96.80 | <001 |
 WHO-guided semen analysis | 4 | −0.186 (−0.53, 0.16) | 0.30 | 98.30 | <001 |
Semen analysis method PM10 | |||||
 CASA | 3 | −0.164 (−0.39, 0.06) | 0.15 | 95.96 | <001 |
 WHO-guided semen analysis | 4 | −0.162 (−0.45, 0.12) | 0.27 | 97.60 | <001 |
Region PM2.5 | |||||
 America | 2 | −0.156 (−0.27, 0.03) | 0.01 | 0.00 | 0.74 |
 Asia | 5 | −0.211 (−0.46, 0.04) | 0.10 | 98.76 | <001 |
 Europe | 1 | −0.194 (−0.35, 0.02) | 0.02 | 0.00 | <001 |
Region PM10 | |||||
 America | 1 | −0.092 (−0.46, 0.27) | 0.61 | 0.00 |  |
 Asia | 5 | −0.175 (−0.38, 0.04) | 0.11 | 98.18 | 0.38 |
 Europe | 1 | −0.193 (−0.35, 0.02) | 0.02 | 0.00 | <001 |