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Table 2 Maternal characteristics associated with dietary nitrite intake, National Birth Defects Prevention Study Controls, 1997-2004

From: Maternal characteristics associated with the dietary intake of nitrates, nitrites, and nitrosamines in women of child-bearing age: a cross-sectional study

  Nitrite intake (mg/day)   Odds ratios and 95% confidence intervalsb
  Quartile 1a Quartile 2 Quartile 3 Quartile 4    
  0.10123 - 1.12224 1.12225 - 1.53386 1.53386 - 2.1305 >2.1305 p-value 4th quartile compared to the 1st quartile
  n % n % n % n %   Crude Adjustedb
Race/Ethnicity            
   White non-Hispanic 1044 29.9 1016 29.1 889 25.4 548 15.7 <0.0001 1.0 1.0
   Black non-Hispanic 155 23.5 138 20.9 182 27.6 185 28.0   2.3 (1.8,2.9) 1.9 (1.3,2.7)
   Hispanic 166 12.8 214 16.5 305 23.6 610 47.1   7.0 (5.7,8.6) 6.2 (4.3,9.0)
   Asian/Pacific Islander 33 19.5 42 24.9 36 21.3 58 34.3   3.3 (2.2,5.2) 10.3 (5.4,19.6)
   Other 45 25.6 40 22.9 40 22.9 50 28.6   2.1 (1.4,3.2) 2.2 (1.2,4.2)
   Missing 12 54.5 4 18.3 3 13.6 3 13.6   --- ---
State/Area of residence            
   Texas 106 15.4 128 18.7 171 24.9 282 41.0 <0.0001 1.0 1.0
   Arkansas 145 20.5 152 21.5 196 27.6 215 30.4   0.56 (0.41,0.76) 0.88 (0.55,1.4)
   California 149 19.1 145 18.5 199 25.4 289 37.0   0.73 (0.54,0.98) 0.49 (0.32,0.76)
   Georgia 165 27.0 155 25.3 153 25.0 139 22.7   0.28 (0.20,0.38) 0.67 (0.42,1.1)
   Iowa 184 28.5 155 24.0 171 26.4 136 21.1   0.11 (0.08,0.16) 0.30 (0.18,0.50)
   Massachusetts 234 31.5 264 35.6 175 23.6 69 9.3   0.31 (0.23,0.43) 0.50 (0.30,0.82)
   New Jersey 156 27.6 145 25.6 135 23.8 130 23.0   0.22 (0.16,0.3) 0.51 (0.31,0.86)
   New York 161 30.7 143 27.2 125 23.8 96 18.3   0.32 (0.23,0.43) 0.54 (0.33,0.89)
   North Carolina 74 25.3 87 29.8 73 25.0 58 19.9   0.29 (0.20,0.44) 0.45 (0.24,0.82)
   Utah 81 31.4 80 31.0 57 22.1 40 15.5   0.19 (0.12,0.29) 0.22 (0.12,0.41)
Dietary folate equivalent (μg/day)            
   <319 670 27.7 398 27.6 267 18.5 105 7.3 <0.0001 1.0 1.0
   319-464.9 369 25.2 440 30.0 410 28.0 246 16.8   4.3 (3.3,5.5) 1.9 (1.3,2.6)
   465 - 685.5 267 18.2 374 25.5 430 29.4 394 26.9   9.4 (7.3,12.2) 1.8 (1.3,2.6)
   > 685.5 149 10.3 242 16.7 348 24.0 709 49.0   30.4 (23.2,39.8) 2.3 (1.5,3.3)
Maternal household income (dollars annually)            
   ≥50,000 559 30.5 582 31.7 452 24.6 243 13.2 <0.0001 1.0 1.0
   40-49,999 117 27.7 119 28.1 106 25.1 81 19.1   1.6 (1.2,2.2) 1.0 (0.66,1.6)
   30-39,999 138 25.5 130 24.0 143 26.4 131 24.1   2.2 (1.6,2.9) 1.4 (0.92,2.0)
   20-29,999 168 22.6 178 23.9 188 25.2 211 28.3   2.9 (2.2,3.7) 1.2 (0.81,1.7)
   10-19.999 132 18.3 133 18.4 192 26.5 266 36.8   4.6 (3.6,6.0) 1.0 (0.68,1.5)
   < 10,000 196 21.1 166 17.8 201 21.6 368 39.5   4.3 (3.4,5.4) 0.71 (0.48,1.1)
   Missing 145 23.5 146 23.6 173 28.0 154 24.9   --- ---
Maternal education (years at school)            
   16+ 538 29.4 585 32.0 456 24.9 251 13.7 <0.0001 1.0 1.0
   13-15 374 24.3 388 25.2 428 27.8 352 22.7   2.0 (1.6,2.5) 1.3 (0.98,1.8)
   12 356 24.7 316 21.9 332 23.0 438 30.4   2.6 (2.1,3.2) 1.2 (0.88,1.7)
   9-11 145 20.8 112 16.1 171 24.5 269 38.6   4.0 (3.1,5.1) 1.2 (0.79,1.9)
   0-8 31 11.2 47 17.0 63 22.7 136 49.1   9.4 (6.2,14.3) 2.9 (1.4,5.8)
   Missing 11 36.7 6 20.0 5 16.7 8 26.7   --- ---
Dietary Fat (% of daily calories)            
   ≤ 30% 950 29.4 827 25.6 756 23.4 702 21.6 <0.0001 1.0 1.0
   >30% 505 19.6 627 24.2 699 27.1 752 29.1   2.0 (1.7,2.3) 8.7 (6.9,11.0)
Pre-pregnancy BMI            
   Normal weight (18.5 < 25.0) 882 28.1 820 26.1 734 23.4 705 22.4 <0.0001 1.0 ---
   Under weight (<18.5) 80 25.4 74 23.5 80 25.4 81 25.7   1.3 (0.92,1.8) ---
   Over weight (25.0 < 30.0) 286 23.0 320 25.7 332 26.7 307 24.6   1.3 (1.1,1.6) ---
   Obese (≥30.0) 184 20.7 198 22.3 257 28.9 249 28.1   1.7 (1.4,2.1) ---
   Missing 23 10.0 42 18.3 52 22.8 112 48.9   --- ---
Folic acid containing supplements            
   No 600 23.1 558 21.4 646 24.8 799 30.7 <0.0001 1.0 ---
   Yes 846 26.6 888 27.9 799 25.1 650 20.4   0.57 (0.50,0.67) ---
   Missing 9 28.1 8 25.0 10 31.3 5 15.6   --- ---
Multivitamin use            
   No 891 25.0 951 26.6 898 25.2 829 23.2 <0.0001 1.0 ---
   Yes 556 25.0 502 22.6 552 24.8 613 27.6   1.2 (1.0,1.4) ---
   Missing 8 30.8 1 3.8 5 19.2 12 46.2   --- ---
Age at conception (years)            
   20-24 325 24.2 307 22.9 323 24.1 386 28.8 <0.0001 1.0  
   <20 204 24.7 165 20.0 185 22.3 273 33.0   1.1 (0.89,1.4) ---
   25-29 379 24.3 409 26.2 391 25.0 382 24.5   0.85 (0.69,1.0) ---
   30-34 372 26.1 383 26.8 382 26.7 291 20.4   0.66 (0.53,0.81) ---
   35+ 175 26.5 190 28.7 174 26.3 122 18.5   0.59 (0.44,0.77) ---
  1. aReferent category is nitrite intake at the lowest quartile of intake (<1.2225 mg.day)
  2. bOnly presented for variables included in the final multinomial logistic regression model
  3. cAdjusted for tertiles of daily caloric intake, race/ethnicity, state of residence, maternal education, dietary fat intake, maternal household income, and dietary folate as dietary folate equivalents
  4. Note: p-value excludes missing values
  5. Note: missing categories contain refuse, don't know, and missing