| 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 | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   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 | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   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 | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   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) | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   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) | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   < 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 | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   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) | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   ≥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 | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   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 | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   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) | --- |