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Table 2 Low birth weight prevalence rate ratios (PRR) associated with maternal sociodemographic and social environmental characteristics. Argentina, Brazil, Chile, Colombia, Costa Rica, Guatemala, Mexico and Peru; 2014

From: Urban social environment and low birth weight in 360 Latin American cities

Cities (n = 360) Low birth weight (<  2500 g)
Sub-cities (n = 1321) Model 1 Model 2 Model 3 Model 4
Cells (n = 19,375) PRR (95% CI)
Maternal age; years
 25–29 Ref. Ref. Ref. Ref.
  ≤ 19 1.21 (1.19, 1.22) 1.21 (1.19, 1.22) 1.21 (1.19, 1.22) 1.21 (1.19, 1.22)
 20–24 1.02 (1.01, 1.03) 1.02 (1.01, 1.03) 1.02 (1.01, 1.03) 1.02 (1.01, 1.03)
 30–34 1.11 (1.09, 1.12) 1.11 (1.09, 1.12) 1.11 (1.09, 1.12) 1.10 (1.09, 1.12)
 35+ 1.35 (1.33, 1.36) 1.35 (1.33, 1.36) 1.35 (1.33, 1.36) 1.35 (1.33, 1.36)
Maternal education
 Completed Secondary and above Ref. Ref. Ref. Ref.
 At least Primary; Less than completed Secondary 1.00 (0.99, 1.00) 1.00 (0.99, 1.01) 1.00 (0.99, 1.01) 1.00 (0.99, 1.00)
 Less than Primary 1.12 (1.10, 1.13) 1.12 (1.11, 1.13) 1.12 (1.11, 1.13) 1.12 (1.10, 1.13)
 Sub-city educational attainment, z-score 1.04 (1.03, 1.04) 1.04 (1.03, 1.04) 1.04 (1.03, 1.04)
 City social environment index, z-score 1.01 (0.98, 1.03) 1.02 (1.00, 1.04)
 City gross domestic product, z-score    0.99 (0.97, 1.01) 0.99 (0.98, 1.01)
 City population size, z-score    1.08 (0.99, 1.17) 1.06 (1.01, 1.12)
Countries
 Peru Ref. Ref. Ref. Ref.
 Argentina 1.37 (1.26, 1.49)
 Brazil 1.60 (1.49, 1.71)
 Chile 1.13 (1.02, 1.25)
 Colombia 1.51 (1.39, 1.64)
 Costa Rica 1.42 (1.08, 1.86)
 Guatemala 3.11 (2.59, 3.73)
 Mexico 1.10 (1.02, 1.18)
Random parameters
 City variance intercept (std. error) 0.054 (0.005) 0.056 (0.005) 0.055 (0.005) 0.018 (0.002)
 Sub city variance intercept (std. error) 0.007 (0.001) 0.006 (0.001) 0.006 (0.001) 0.005 (0.001)
 PCV (city) 5.3a + 3.7 1.8 67.3
 PCV (sub-city) 12.5b 14.3 0.0 16.7
  1. Cells of LBW aggregated by maternal education and maternal age nested within sub-cities and within cities. Outcome: LBW (< 2500 g) reported as prevalence rate ratios (PRR) considering counts of LBW and total births (offset). Empty model includes random intercepts for sub cities and cities (not shown); model 1 includes maternal age and maternal education; model 2 adds sub-city population educational attainment to model 1; model 3 adds city social environment index, gross domestic product and population size of cities to model 2; model 4 adds countries as fixed effects. PCV: Proportional change in variance compared to preceding model. The positive sign indicates and increase in variance; a Calculated based by comparing to city variance intercept (std. error) of the empty model (0.057 (0.005); not shown); b Calculated based by comparing to sub-city variance intercept (std. error) of the empty model (0.008 (0.001); not shown)