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Table 1 Association between background factors, birth weight and low birth weight (LBW)

From: Factors associated with birthweight and adverse pregnancy outcomes among children in rural Guinea-Bissau - a prospective observational study

  Background factors and low birth weight LBW < 2.500 g Background factors and birth weight
Background factors Observationsa LBW n(%) Prevalence ratio [95% CI]b P-value Mean birth weight in kg (SD) 95% CI P-valuec
Total N = 628 104 (17)    2.89 (0.43)   
Sex 0.12    < 0.001
 Boys 313 46 (15) Reference   2.95 (0.43) [2.90, 3.00]  
 Girls 315 58 (18) 1.25 [0.94, 1.67]   2.83 (0.43) [2.79, 2.88]  
Twinning < 0.001    < 0.001
 Singleton 617 98 (16) Reference   2.90 (0.43) [2.87, 2.93]  
 Twin 11 6 (55) 3.43 [1.96, 6.03]   2.34 (0.31) [2.15, 2.52]  
Region < 0.001    0.004
 Oio 347 77 (22) Reference   2.84 (0.44) [2.79, 2.88]  
 Biombo 132 13 (10) 0.44 [0.25, 0.79]   2.96 (0.42) [2.89, 3.03]  
 Cacheu 149 14 (9) 0.42 [0.25, 0.73]   2.95 (0.39) [2.89, 3.01]  
Maternal BCG-scar statusd     0.70    0.92
 Scar present 401 68 (17) 1.06 [0.78, 1.46]   2.89 (0.42) [2.85, 2.93]  
 No scar 226 36 (16) Reference   2.89 (0.44) [2.83, 2.95]  
Socioeconomic factors        
Roof type     0.57    0.45
 Straw roof 134 20 (15) Reference   2.91 (0.47) [2.84, 2.99]  
 Hard roof 492 84 (17) 1.14 [0.72, 1.83]   2.88 (0.42) [2.85, 2.92]  
Radio     0.62    0.33
 Yes 549 91 (17) Reference   2.90 (0.43) [2.86, 2.93]  
 No 63 9 (14) 0.86 [0.48, 1.54]   2.85 (0.40) [2.75, 2.95]  
Solar panel/Generator     0.18    0.62
 Yes 280 54 (19) 1.30 [0.88, 1.93]   2.88 (0.45) [2.83, 2.93]  
 No 338 50 (15) Reference   2.89 (0.42) [2.85, 2.94]  
Mobile phone     0.01    < 0.001
 Yes 369 53 (14) Reference   2.93 (0.42) [2.89, 2.97]  
 No 232 48 (21) 1.44 [1.07, 1.93]   2.83 (0.45) [2.77, 2.88]  
Toilet     0.50    0.92
 No toilet 152 23 (15) 0.88 [0.62, 1.26]   2.89 (0.43) [2.82, 2.96]  
 Latrine/Toilet in the house 473 81 (17) Reference   2.89 (0.43) [2.85, 2.93]  
Maternal School     0.28    0.50
 0 years of school 289 56 (19) Reference   2.86 (0.42) [2.82, 2.91]  
 1–4 years of school 171 22 (13) 0.66 [0.40, 1.10]   2.91 (0.41) [2.84, 2.97]  
 More than 4 years of school 133 20 (15) 0.78 [0.43, 1.41]   2.92 (0.45) [2.84, 3.00]  
Maternal age at birth of child     0.30    < 0.001
 < 20 years 166 37 (22) Reference   2.76 (0.41) [2.70, 2.82]  
 20–27 years 166 27 (16) 0.73 [0.43, 1.23]   2.91 (0.43) [2.84, 2.97]  
 28–35 years 162 27 (17) 0.75 [0.46, 1.23]   2.92 (0.44) [2.86, 2.99]  
 > = 36 years 132 13 (10) 0.44 [0.19, 1.02]   2.99 (0.41) [2.92, 3.06]  
Number of prenatal consultations     < 0.001    0.002
 None 121 34 (28) Reference   2.79 (0.46) [2.71, 2.87]  
 1 or 2 179 27 (15) 0.54 [0.36, 0.79]   2.89 (0.39) [2.83, 2.95]  
 3 or more 271 36 (13) 0.47 [0.35, 0.63]   2.92 (0.44) [2.87, 2.97]  
Maternal MUAC     < 0.001    < 0.001
 1st quartile (= < 240 mm) 156 40 (26) Reference   2.74 (0.41) [2.68, 2.80]  
 2nd quartile (242–256 mm) 159 28 (18) 0.69 [0.48, 0.99]   2.88 (0.40) [2.82, 2.94]  
 3rd quartile (258–276 mm) 149 19 (13) 0.50 [0.27, 0.91]   2.94 (0.45) [2.87, 3.01]  
 4th quartile (> = 278 mm) 150 16 (11) 0.42 [0.27, 0.64]   2.99 (0.43) [2.92, 3.06]  
Number of pregnancies     0.009    0.001
 1 133 33 (25) Reference   2.76 (0.39) [2.69, 2.82]  
 2 or 3 234 31 (13) 0.53 [0.36, 0.79]   2.93 (0.41) [2.88, 2.98]  
 4 or 5 166 31 (19) 0.75 [0.44, 1.30]   2.86 (0.46) [2.79, 2.93]  
 > 5 90 9 (10) 0.40 [0.19, 0.87]   3.03 (0.43) [2.94, 3.11]  
Time of pregnancy registration     0.59    0.14
 1st quartile (= < 77 days) 155 27 (17) Reference   2.88 (0.44) [2.81, 2.95]  
 2nd quartile (78–118 days) 154 23 (15) 0.86 [0.53, 1.38]   2.85 (0.39) [2.79, 2.91]  
 3rd quartile (119–152 days) 160 32 (20) 1.15 [0.76, 1.73]   2.88 (0.46) [2.80, 2.95]  
 4th quartile (> = 153 days) 158 22 (14) 0.80 [0.46, 1.40]   2.95 (0.42) [2.89, 3.02]  
Time of weighing     0.86    0.34
<  24 h 193 31 (16) Reference   2.92 (0.46) [2.86, 2.99]  
 24 - < 48 h 264 43 (16) 1.01 [0.63, 1.64]   2.86 (0.39) [2.81, 2.91]  
 48–72 h 167 30 (18) 1.12 [0.69, 1.82]   2.90 (0.45) [2.83, 2.97]  
Place of birth     0.87    0.41
 Home 421 70 (17) Reference   2.89 (0.44) [2.85, 2.93]  
 Health Center 140 22 (16) 0.95 [0.62, 1.44]   2.90 (0.40) [2.83, 2.97]  
 Hospital 54 9 (17) 1.00 [0.63, 1.60]   2.93 (0.46) [2.81, 3.05]  
 Other 12 3 (25) 1.50 [0.54, 4.21]   2.73 (0.41) [2.50, 2.96]  
Season of birthd     0.45    0.29
 Dry Season 313 49 (16) Reference   2.87 (0.40) [2.83, 2.92]  
 Rainy Season 315 55 (17) 1.12 [0.84, 1.48]   2.91 (0.46) [2.86, 2.96]  
  1. a) 628 of 633 enrolled children were weighed. Numbers do not add up to 628 due to missing information on background factors for some children
  2. b) Standard error adjusted for cluster
  3. c) P-value from linear regression of birthweight against the grouped background variables, corrected for intra-cluster correlation using robust standard errors
  4. d) Rainy season: June–November; Dry season: December–May