Table 3.
Multi-level multiple regression analysis of determinants of birth weight (as a continuous outcome) (n = 327877)
| Model 1 | Model 2 | Model 3 | Model 4 | Model 5 | Model 6 | |
| Intercept | 3562.58 | 3563.328 | 3624.578 (10.368) | 3511.860 (8.732) | 3518.116 (8.786) | 3519.353 (8.713) |
| (2.373) | (2.384) | |||||
| Year of birth | 3.653 (0.363) | 3.943 (0.365) | 4.076 (0.335) | 3.928 (0.336) | 1.867 (0.337) | |
| Fixed effects | Beta (SE) | |||||
| Neighbourhood economic status | ||||||
| Very high level of resources | - | - | - | - | ||
| High level of resources | -27.806 (10.938) | -7.206 (9.202) | -5.380 (9.064) | -4.193 (9.180) | ||
| Medium to high level of resources | -36.764 (10.850) * | -0.982 (9.024) | 2.372 (8.890) | 6.625 (9.002) | ||
| Medium level of resources | -48.418 (10.776) * | -2.295 (8.961) | 2.573 (8.837) | 10.105 (8.942) | ||
| Medium to low level of resources | -66.231 (10.845) * | -8.818 (9.025) | -2.862 (8.908) | 8.061 (9.006) | ||
| Low level of resources | -91.652 (11.000) * | -23.591 (9.148) | -14.204 (9.049) | -1.210 (9.135) | ||
| Very low level of resources | -138.568 (11.412) * | -56.813 (9.494)* | -44.187 (9.425)* | -33.053 (9.481)* | ||
| Poor | -171.387 (12.845) * | -75.971 (10.590)* | -62.003 (10.593) * | -56.028 (10.587) * | ||
| Maternal height | 16.068 (0.143) * | 15.908 (0.145) * | 16.145 (0.144) * | |||
| Length of gestation | ||||||
| 22–28 weeks | -2580.491 (21.378) * | -2581.771 (21.616) * | -2566.803 (21.657) * | |||
| 29–32 weeks | -1813.587 (12.011) * | -1815.726 (12.137) * | -1796117 (12.190) * | |||
| 33–36 weeks | -858.069 (4.653) * | -859.875 (4.697) * | -851.399 (4.692) * | |||
| 37–41 weeks (reference) | - | - | - | |||
| ≥ 42 weeks | 293.570 (8.623) * | 294.794 (8.729) * | 296.171 (8.700) * | |||
| Parity | 147.626 (1.801) * | 149.529 (1.818) * | 150.013 (1.812) * | |||
| Maternal education | ||||||
| Elementary (reference) | -43.699 (3.246) * | |||||
| Secondary (2 yrs) | -10.525 (2.448) * | |||||
| Secondary (3–4 yrs) | - | |||||
| University | -6.009 (2.929) | |||||
| Maternal smoking habits (cig/day) | ||||||
| 0 (reference) | - | |||||
| 1–9 | -131.976 (3.041) * | |||||
| ≥ 10 | -199.493 (3.970) * | |||||
| Random effects | Variance components | |||||
| Intercept variance; individuals | 300378.500 | 300183.600 | 300270.600 | 223262.800 | 223139.700 | 219758.000 |
| (SE) | (744.144) | (744.159) | (744.340) | (587.044) | (592.469) | (586.149) |
| Intercept variance;neighbourhood | 2498.777 | 2427.644 | 827.088 | 361.735 | 324.721 | 347.552 |
| (SE) | (189.361) | (191.355) | (84.832) | (49.094) | (46.965) | (48.430) |
| Slope variance; year of birth | NA | 11.007 | 9.691 | 8.478 | 7.598 | 8.049 |
| (SE) | (3.970) | (3.893) | (3.282) | (3.263) | (3.289) | |
| Covariance | NA | 96.479 | 16.604 | 4.691 (9.026) | 4.203 (8.796) | 7.802 (8.986) |
| (SE) | (20.631) | (13.071) | ||||
| ICC | 0.83% | |||||
| Reduction of neighbourhood intercept variance | 66.9% | 85.5% | 87.0% | 86.1% | ||
NA = not applicable, ICC = intra-class correlation; SE = standard error, * = WALD-statistics > 3