Meta-analyses of small for gestational age, summary risk estimate (SRE) by exposure category for all studies, sensitivity analyses and final result from higher validity studies
| (1) Lifting <12 kg | (2) Lifting unspecified weight or ≥5 kg | (3) Heavy lifting or ≥10 kg, ≤10x per day or rarely | (4) Heavy lifting or ≥10 kg, unspecified frequency or ≥1x per day | (5) Heavy lifting or ≥10 kg, ≥10x per day or often | |||||||||||
| N | SRE | (95% CI) | N | SRE | (95% CI) | N | SRE | (95% CI) | N | SRE | (95% CI) | N | SRE | (95% CI) | |
| All studies | 3 | 0.97 | (0.81 to 1.15) | 3 | 1.04 | (0.76 to 1.44) | 8 | 1.07 | (0.90 to 1.29) | 5 | 1.24 | (0.96 to 1.59) | 7 | 1.10 | (1.01 to 1.19)* |
| Sensitivity analyses | |||||||||||||||
| Developed countries and study period >1975 | 3 | 0.97 | (0.81 to 1.15) | 3 | 1.04 | (0.76 to 1.44) | 6 | 1.11 | (0.92 to 1.34) | 4 | 1.25 | (0.94 to 1.65) | 6 | 1.10 | (1.01 to 1.20)* |
| Response rate ≥80% | 3 | 0.97 | (0.81 to 1.15) | 2 | 0.91 | (0.47 to 1.76) | 4 | 1.05 | (0.86 to 1.27) | 2 | 1.33 | (0.77 to 2.30) | 5 | 1.09 | (0.99 to 1.20) |
| Prospective assessment of exposure | 1 | 0.56 | (0.17 to 1.79) | 2 | 0.84 | (0.44 to 1.58) | 6 | 1.09 | (0.86 to 1.38) | 2 | 1.15 | (0.68 to 1.94) | 5 | 1.04 | (0.86 to 1.25) |
| Quantitative definition of lifting (weight, frequency) | 1 | 0.56 | (0.17 to 1.79) | 0 | 6 | 1.00 | (0.92 to 1.09) | 1 | 1.2 | (0.6 to 2.2) | 5 | 1.03 | (0.88 to 1.20) | ||
| Adequate control of personals factors | 3 | 0.97 | (0.81 to 1.15) | 3 | 1.04 | (0.76 to 1.44) | 4 | 1.18 | (0.82 to 1.70) | 4 | 1.25 | (0.94 to 1.65) | 5 | 1.11 | (1.02 to 1.21)* |
| Adequate control of other occupational exposures | 2 | 0.98 | (0.82 to 1.16) | 1 | 1.16 | (0.92 to 1.46) | 2 | 0.97 | (0.74 to 1.26) | 1 | 1.03 | (0.71 to 1.51) | 2 | 1.02 | (0.70 to 1.49) |
| Final result | |||||||||||||||
| From studies with validity score >12 | 3 | 0.97 | (0.81 to 1.15) | 2 | 0.91 | (0.47 to 1.76) | 4 | 0.99 | (0.91 to 1.08) | 1 | 1.03 | (0.71 to 1.51) | 4 | 1.03 | (0.87 to 1.21) |
| Test of heterogeneity†: Q, p-value (p), I2 | Q=1.03, p=0.60, I2=0% | Q=2.69, p=0.10, I2=63% | Q=1.21, p=0.75, I2=0% | Q=3.34, p=0.50,† I2=0% † | Q=2.83, p=0.42, I2=0% | ||||||||||
Final results, from high validity studies, are in bold.
*P-value <0.05
†Calculated for all studies if only one study has a validity score >12.