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Table 3 Maternal characteristics associated with total dietary nitritea 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

  Total Nitrite intake (mg/day)   Odds ratios and 95% confidence intervalsc
  Quartile 1b Quartile 2 Quartile 3 Quartile 4    
  0.31362-2.63578 2.63579 - 3.69108 3.69109 - 5.21853 5.21854 - 59.0717 p-value 4th quartile compared to the 1st quartile
  n % n % n % n %   Crude Adjustedd
Race/Ethnicity            
   White non-Hispanic 1024 29.3 988 28.3 903 25.9 577 16.5 <0.0001 1.0 1.0
   Black non-Hispanic 132 20 134 20.4 151 22.9 242 36.7   3.3 (2.6,4.1) 2.6 (1.8,3.6)
   Hispanic 222 17.2 263 20.3 315 24.3 494 38.2   3.9 (3.3,4.8) 2.0 (1.5,2.8)
   Asian/Pacific Islander 28 16.7 19 11.3 39 23.2 82 48.8   5.2 (3.3, 8.1) 9.2 (5.1,16.7)
   Other 39 22.3 42 24 43 24.6 51 29.1   2.3 (1.5,3.6) 1.9 (1.1,3.5)
   Missing 8 38.1 6 28.6 1 4.7 6 28.6   --- ---
State/Area of residence            
   Texas 140 20.4 171 24.8 166 24.2 210 30.6 <0.0001 1.0 1.0
   Arkansas 178 25.2 181 25.7 163 23.1 183 26   0.69 (0.51,0.93) 0.76 (0.50,1.2)
   California 176 22.6 162 20.8 188 24.1 253 32.5   0.96 (0.72,1.3) 0.84 (0.57,1.2)
   Georgia 137 22.5 135 22.1 159 26.1 179 29.3   0.24 (0.18,0.34) 0.40 (0.25,0.63)
   Iowa 229 35.4 178 27.6 155 24.0 84 13   0.54 (0.40,0.74) 1.7 (1.1,2.7)
   Massachusetts 173 23.3 213 28.7 215 29.0 141 19   0.97 (0.70,1.3) 1.7 (1.1,2.6)
   New Jersey 114 20.1 141 24.9 145 25.7 166 29.3   0.51 (0.37,0.71) 1.0 (0.65,1.6)
   New York 147 28.1 125 23.8 139 26.5 113 21.6   0.87 (0.64,1.2) 1.5 (0.93,2.3)
   North Carolina 76 26 73 25 66 22.6 77 26.4   0.68 (0.46,0.99) 1.3 (0.76,2.2)
   Utah 83 32.2 73 28.3 56 21.7 46 17.8   0.37 (0.24,0.56) 0.51 (0.29,0.90)
Dietary folate equivalent (μg/day)            
   <319 739 51.4 427 29.6 208 14.5 64 4.5 <0.0001 1.0 1.0
   319-464.9 349 23.9 463 31.6 441 30.1 210 14.4   6.9 (5.1,9.4) 4.0 (2.9,5.7)
   465-685.5 232 15.9 352 24.1 452 30.9 426 29.1   21.2 (15.7,28.7) 6.4 (4.5,9.1)
   >685.5 133 9.2 210 14.5 351 24.3 752 52   65.3 (47.6,89.5) 8.7 (6.0,12.6)
Folic acid containing supplements            
   No 646 24.9 606 23.3 625 24.0 722 27.8 <0.0001 1.0 1.0
   Yes 799 25.1 837 26.3 820 25.8 722 22.7   0.81 (0.70,0.94) 1.1 (0.89,1.3)
   Missing 8 25 9 28.1 7 21.9 8 25   --- ---
Maternal education (years at school)            
   16+ 473 25.9 517 28.3 458 25.0 381 20.8 <0.0001 1.0 1.0
   12-15 390 25.3 393 25.5 400 26.0 357 23.2   1.1 (093,1.4) 0.80 (0.61,1.0)
   12 377 26.2 346 24.1 349 24.3 366 25.5   1.2 (0.99,1.5) 0.55 (0.42,0.73)
   9-11 164 23.5 142 20.4 163 23.4 228 32.7   1.7 (1.4,2.2) 0.49 (0.34,0.70)
   0-8 42 15.2 46 16.7 74 26.8 114 41.3   3.4 (2.3,4.9) 0.87 (0.46,1.7)
   Missing 7 24.1 8 27.6 8 27.6 6 20.7   --- ---
Dietary Fat (% of daily calories)            
   < 30% 844 26.1 773 23.9 786 24.4 825 25.6 0.0280 1.0 1.0
   >30% 609 23.6 679 26.3 666 25.8 627 24.3   1.1 (0.91,1.2) 2.5 (2.0,3.0)
Pre-pregnancy BMI            
   Normal weight (18.5 < 25.0) 843 26.9 772 24.6 772 24.6 749 23.9 0.1870 1.0 1.0
   Under weight (<18.5) 72 22.9 80 25.5 78 24.8 84 26.8   1.3 (0.94,1.8) 1.1 (0.73,1.7)
   Over weight (25.0 < 30.0) 301 24.2 327 26.2 323 26.0 293 23.6   1.1 (0.91,1.3) 1.3 (0.80,2.0)
   Obese (>30.0) 203 22.9 231 26 213 24.0 240 27.1   1.3 (1.1,1.6) 1.8 (1.1,2.9)
   Missing 34 14.9 42 18.5 66 28.9 86 37.7   --- ---
Maternal household income (dollars annually)            
   ≥50,000 484 26.4 516 28.1 474 25.8 361 19.7 <0.0001 1.0 ---
   40-49,999 116 27.4 122 28.8 94 22.3 91 21.5   1.1 (0.77,1.4) ---
   30-39,999 150 27.7 125 23.1 148 27.4 118 21.8   1.1 (0.80,1.4) ---
   20-29,999 176 23.6 184 24.7 204 27.4 181 24.3   1.4 (1.1,1.8) ---
   10-19.999 157 21.7 150 20.9 180 24.9 235 32.5   2.0 (1.6,2.6) ---
   < 10,000 211 22.8 189 20.4 207 22.4 319 34.4   2.0 (1.6,2.5) ---
   Missing 159 25.8 166 26.9 145 23.5 147 23.8   --- ---
Multivitamin use            
   No 882 24.7 914 25.7 905 25.4 863 24.2 0.2470 1.0 ---
   Yes 563 25.4 537 24.2 539 24.2 581 26.2   1.1 (0.91,12) ---
   Missing 8 32 1 4 8 32.0 8 32   --- ---
Age at conception            
   20-24 377 28.2 320 23.9 314 23.4 328 24.5 0.002 1.0  
   <20 230 27.9 200 24.4 188 22.8 205 24.9   1.0 (0.81,1.3) ---
   25-29 389 24.9 385 24.7 386 24.8 400 25.6   1.2 (0.96,1.4) ---
   30-34 317 22.2 375 26.3 400 28.1 334 23.4   1.2 (0.98,1.5) ---
   35+ 140 21.2 172 26 164 24.8 185 28   1.5 (1.2,1.9) ---
  1. aTotal dietary nitrite = 5% dietary nitrate + dietary nitrite
  2. bReferent category is total nitrite intake at the lowest quartile of intake (<2.63578 mg/day)
  3. cOnly presented for variables included in the final multinomial logistic regression model
  4. dAdjusted for tertiles of daily caloric intake, race/ethnicity, maternal education, state of residence, dietary fat intake, pre-pregnancy body mass index, and folic acid supplementation
  5. Note: p-value excludes missing values
  6. Note: missing categories contain refuse, don't know, and missing