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Table 5 Multivariable analysis of risk factors for LBW, 1997/98 and 2010 São Luís birth cohorts

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

  1997/98 Cohort 2010 Cohort
Variable Odds ratio* 95% Confidence interval p* Odds ratio* 95% Confidence interval p**
Maternal age (years)    0.082    0.142
 <18 1.51 (0.99; 2.29)   1.10 (0.75; 1.59)  
 18 – 19 0.78 (0.49; 1.24)   1.09 (0.77; 1.55)  
 20 – 34 1 Reference   1 Reference  
 ≥35 1.19 (0.52; 2.70)   1.55 (1.06; 2.27)  
Newborn’s sex    0.686    0.017
 Male 1 Reference   1 Reference  
 Female 1.06 (0.78; 1.44)   1.29 (1.04; 1.59)  
Family income    0.107    0.119
 ≤1 1.52 (0.97; 2.37)   1.41 (0.99; 2.03)  
 1- 3 1.21 (0.83; 1.76)   1.38 (1.04; 1.84)  
 >3 1 Reference   1 Reference  
 Missing 1.82 (1.03; 3.22)   1.31 (0.92; 1.84)  
Adequacy of prenatal care use    0.455    <0.001
 Adequate 1 Reference   1 Reference  
 Inadequate 0.76 (0.53; 1.07)   0.86 (0.67; 1.10)  
 No care 0.98 (0.55; 1.77)   2.79 (1.60; 4.86)  
 Missing 0.90 (0.26; 3.10)   0.78 (0.46; 1.34)  
Maternal smoking during pregnancy    0.007    <0.001
 No 1 Reference   1 Reference  
 Yes 2.30 (1.25; 4.23)   2.51 (1.63; 3.84)  
Parity    0.003    <0.001
 1 1.66 (1.13; 2.43)   1.57 (1.20; 2.05)  
 2 1 Reference   1 Reference  
 ≥3 0.83 (0.50; 1.38)   1.10 (0.53; 1.77)  
Category of delivery care    0.050    0.916
 Private 1 Reference   1 Reference  
 Public 1.94 (0.99; 3.78)   0.97 (0.58; 1.60)  
Type of delivery    0.064    0.403
 Vaginal 1 Reference   1 Reference  
 Cesarean 1.38 (0.98; 1.95)   1.12 (0.82; 1.53)  
  1. *Odds Ratio (OR) calculated by multiple logistic regression.
  2. **p-value calculated by the log likelihood ratio test.