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Table 4 Anthropometric Risk Factors for Preterm birth

From: Mid-arm muscle area and anthropometry predict low birth weight and poor pregnancy outcomes in Tanzanian women with HIV

Characteristics N Univariate Multivariatea
RR (95% CI) P-Value RR (95% CI) P-Value
Maternal weight change - overall (slope)
 Tertile 1 56 Reference 0.68^   
 Tertile 2 61 1.06 (0.75, 1.50)    
 Tertile 3 67 1.20 (0.86, 1.68)    
Maternal weight change - 2nd trimester(slope)
 Tertile 1 47 Reference 0.32^   
 Tertile 2 60 1.24 (0.87, 1.78)    
 Tertile 3 63 1.34 (0.94, 1.92)    
BMI change - overall (slope)
 Tertile 1 58 Reference 0.21^ Reference 0.14^
 Tertile 2 59 0.99 (0.70, 1.39)   0.99 (0.70, 1.39)  
 Tertile 3 67 1.16 (0.83, 1.61)   1.16 (0.83, 1.61)  
MAMA (mean) (cm)
  ≤ 33.1 167 Reference   Reference  
  > 33.1 134 0.84 (0.68, 1.04) 0.07^ 0.85 (0.69, 1.04) 0.04&
MAMA change - overall (slope)
 Tertile 1 76 Reference 0.93^   
 Tertile 2 113 1.45 (1.10, 1.90)    
 Tertile 3 73 0.96 (0.71, 1.30)    
MAMA change - 2nd trimester (slope)
 Tertile 1 68 Reference 0.61^   
 Tertile 2 48 0.68 (0.48, 0.97)    
 Tertile 3 68 1.00 (0.73, 1.37)    
MUAC (mean) (cm)
  < 26 cm 189 Reference   Reference  
  ≥ 26 cm 112 0.68 (0.55, 0.85) 0.002^ 0.70 (0.56, 0.86) 0.002^
MUAC change - overall (slope)
 Tertile 1 71 Reference 0.82^   
 Tertile 2 37 0.51 (0.35, 0.74)    
 Tertile 3 64 0.89 (0.65, 1.23)    
MUAC change - 2nd trimester (slope)
 Tertile 1 67 Reference 0.86^   
 Tertile 2 34 0.50 (0.34, 0.73)    
 Tertile 3 61 0.90 (0.65, 1.23)    
Adherence to iron supplementation
  < median 219 Reference   Reference  
  ≥ median 140 0.64 (0.52, 0.78) < 0.0001& 0.72 (0.59, 0.89) < 0.0001&
  1. ^ Test for trend
  2. & Association was significantly non-linear. P-value corresponds to test for overall significance
  3. a Multivariate Model adjusted for all variables in the univariate with a p-value less than 0.20 plus gestational age (< 25, ≥ 25 weeks); education (none, 1–4, 5–8, 8+ years), previous pregnancies (0, 1 to 3, 3+), daily food expenditure (< 500 Tsh, > 500 Tsh); previous low birth weight baby, previous baby died with first 7 days, previous stillbirth, previous abortion (less than 7 months), repeated fever during pregnancy. Anthropometric variables (weight, BMI, MAMA) were entered into separate multivariate models. Where both mean and change (slope) variables are significant they were both entered into the same model (e.g. weight and weight change)