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Table 4 Univariable analysis of risk factors for low birth weight, 2010 São Luís birth cohort

From: Low birth weight in São Luís, northeastern Brazil: trends and associated factors

Variables %Low birth weight Odds ratio* 95% Confidence interval p**
Newborn’s sex     0.026
 Male 6.7 1 Reference  
 Female 8.3 1.26 (1.02; 1.56)  
Preterm birth     <0.001
 Yes 40.3 20.92 (16.53; 26.48)  
 No 3.1 1 Reference  
IUGR***     <0.001
 No 3.3 1 Reference  
 Mild 8.0 2.56 (1.97; 4.05)  
 Moderate 15.2 5.27 (3.79; 8.13)  
 Severe 72.2 76.87 (55.40; 106.64)  
Maternal age(years)     0.107
 <18 9.4 1.38 (0.98; 1.95)  
 18 – 19 8.7 1.28 (0.91; 1.78)  
 20 – 34 6.9 1 Referência  
 ≥35 9.1 1.33 (0.92; 1.93)  
Maternal schooling (years)     0.861
 0 to 4 7.0 0.96 (0.54; 1.72)  
 5 to 8 7.2 0.99 (0.66; 1.41)  
 9 to 11 7.7 1.06 (0.78; 1.44)  
 ≥12 7.3 1 Reference  
 Missing 15.4 2.32 (0.50; 10.74)  
Marital status     0.020
 Married 6.3 1 Reference  
 Consensual union 7.3 1.18 (0.89; 1.56)  
 Without a companion 9.5 1.56 (1.13; 2.17)  
Family income (minimum wages)     0.107
 ≤1 8.3 1.37 (0.97; 1.93)  
 1- 3 7.9 1.31 (0.99; 1.72)  
 >3 6.2 1 Reference  
 Missing 7.8 1.29 (0.93; 1.80)  
Maternal smoking during pregnancy     <0.001
 No 7.2 1 Reference  
 Yes 16.1 2.49 (1.65; 3.73)  
Occupation of the family head     0.346
 Non-manual 6.9 1 Reference  
 Skilled manual worker 8.2 1.20 (0.90; 1.60)  
 Unskilled manual worker 6.9 0.98 (0.73; 1.33)  
 Missing 8.5 1.24 (0.68; 2.25)  
Parity     0.003
 1 8.8 1.50 (1.16; 1.93)  
 2 6.0 1 Reference  
 ≥3 6.8 1.14 (0.83; 1.56)  
Adequacy of prenatal care use     <0.001
 Adequate 7.6 1 Reference  
 Inadequate 6.8 0.89 (0.70; 1.12)  
 No care 20.0 3.04 (1.80; 5.11)  
 Missing 6.2 0.80 (0.47; 1.36)  
Category of delivery care     0.293
 Private 6.6 1 Reference  
 Public 7.7 1.17 (0.86; 1.58)  
Type of delivery     0.265
 Vaginal 7.9 1 Reference  
 Cesarean 7.1 0.88 (0.71; 1.09)  
  1. *Odds Ratio (OR) calculated by simple logistic regression.
  2. **p-value calculated by the log likelihood ratio test.
  3. ***IUGR–intrauterine growth restriction based on the birth weight ratio.