| Dietary nitrate intake (mg/day) |  | Odds ratios and 95% confidence intervalsb | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
 | Quartile 1a | Quartile 2 | Quartile 3 | Quartile 4 |  |  |  | |||||
 | <27.06 | 27.07-40.48 | 40.49-60.60 | 61.89-809.64 | p-value | 4th quartile compared to the 1st quartile | ||||||
 | n | % | n | % | n | % | n | % |  | Crude | Adjustedc | |
Race/Ethnicity | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   White non-Hispanic | 991 | 28.4 | 964 | 27.6 | 890 | 25.5 | 647 | 18.5 | <0.0001 | 1.0 | 1.0 | |
   Black non-Hispanic | 130 | 19.7 | 119 | 18.1 | 167 | 25.3 | 243 | 36.9 |  | 2.9 (2.3,3.6) | 2.4 (1.7,3.3) | |
   Hispanic | 267 | 20.6 | 292 | 22.6 | 318 | 24.6 | 417 | 32.2 |  | 2.4 (2.0,2.9) | 1.4 (1.0,1.9) | |
   Asian/Pacific Islander | 25 | 14.9 | 19 | 11.3 | 36 | 21.4 | 88 | 52.4 |  | 5.4 (3.4,8.5) | 4.8 (2.7,8.5) | |
   Other | 34 | 19.4 | 51 | 29.2 | 39 | 22.3 | 51 | 29.1 |  | 2.3 (1.5,3.6) | 1.6 (0.89,2.9) | |
   Missing | 6 | 28.6 | 7 | 33.3 | 2 | 9.5 | 6 | 28.6 |  | --- | --- | |
State/Area of residence | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   Texas | 168 | 24.5 | 192 | 27.9 | 165 | 24.0 | 162 | 23.6 | <0.0001 | 1.0 | 1.0 | |
   Arkansas | 194 | 27.5 | 182 | 25.9 | 168 | 23.8 | 161 | 22.8 |  | 0.86 (0.64,1.2) | 0.79 (0.52,1.2) | |
   California | 191 | 24.5 | 165 | 21.2 | 197 | 25.3 | 226 | 29.0 |  | 1.2 (0.92,1.6) | 0.98 (0.68,1.4) | |
   Georgia | 129 | 21.1 | 127 | 20.8 | 165 | 27.1 | 189 | 31.0 |  | 1.5 (1.1,2.1) | 2.2 (1.4,3.4) | |
   Iowa | 245 | 37.9 | 187 | 28.9 | 147 | 22.8 | 67 | 10.4 |  | 0.30 (0.20,0.40) | 0.37 (0.23,1.4) | |
   Massachusetts | 150 | 20.2 | 192 | 25.9 | 216 | 29.1 | 184 | 24.8 |  | 1.3 (0.94,1.7) | 2.9 (1.9,4.5) | |
   New Jersey | 103 | 18.2 | 122 | 21.5 | 152 | 26.9 | 189 | 33.4 |  | 1.9 (1.4,2.6) | 2.7 (1.7,4.1) | |
   New York | 127 | 24.2 | 126 | 24.0 | 135 | 25.8 | 136 | 26.0 |  | 1.1 (0.80,1.5) | 1.8 (1.1,2.8) | |
   North Carolina | 72 | 24.7 | 81 | 27.7 | 54 | 18.5 | 85 | 29.1 |  | 1.2 (0.84,1.8) | 1.7 (1.1,2.9) | |
   Utah | 74 | 28.7 | 78 | 30.3 | 53 | 20.5 | 53 | 20.5 |  | 0.74 (0.49,1.1) | 0.99 (0.59,1.7) | |
Dietary folate equivalent (μg/day) |  |  |  |  |  |  |  |  |  |  |  | |
   <319 | 725 | 50.4 | 422 | 29.3 | 202 | 14.1 | 89 | 6.2 | <0.0001 | 1.0 | 1.0 | |
   319-464.9 | 351 | 24.0 | 463 | 31.6 | 416 | 28.5 | 233 | 15.9 |  | 5.4 (4.1,7.1) | 3.4 (2.5,4.7) | |
   465-685.5 | 232 | 15.9 | 350 | 23.9 | 451 | 30.9 | 429 | 29.3 |  | 15.1 (11.5,19.8) | 5.5 (4.0,7.6) | |
   > 685.5 | 145 | 10.0 | 217 | 15.0 | 383 | 26.5 | 701 | 48.5 |  | 39.4 (29.7,52.3) | 7.3 (5.1,10.3) | |
Maternal household income (dollars annually) | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   ≥50 K | 442 | 24.1 | 469 | 25.6 | 496 | 27.0 | 428 | 23.3 | <0.0001 | 1.0 | 1.0 | |
   40-49,999 | 120 | 28.4 | 114 | 27.0 | 100 | 23.6 | 89 | 21.0 |  | 0.77 (0.56,1.0) | 0.67 (0.47,0.97) | |
   30-39,999 | 138 | 25.5 | 153 | 28.3 | 134 | 24.8 | 116 | 21.4 |  | 0.87 (0.66,1.1) | 0.71 (0.50,1.0) | |
   20-29,999 | 180 | 24.2 | 203 | 27.2 | 182 | 24.4 | 180 | 24.2 |  | 1.0 (0.81,1.3) | 0.71 (0.52,0.97) | |
   10-19.999 | 165 | 22.9 | 167 | 23.1 | 189 | 26.2 | 201 | 27.8 |  | 1.3 (0.98,1.6) | 0.49 (0.36,0.68) | |
   < 10,000 | 233 | 25.2 | 205 | 22.1 | 198 | 21.4 | 290 | 31.3 |  | 1.3 (1.0,1.6) | 0.43 (0.32,0.59) | |
   Missing | 175 | 28.4 | 141 | 22.9 | 153 | 24.8 | 148 | 24.0 |  | --- | --- | |
Maternal education (years at school) | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   16+ | 436 | 23.8 | 465 | 25.5 | 483 | 26.4 | 445 | 24.3 | 0.0010 | 1.0 | --- | |
   13-15 | 399 | 25.9 | 393 | 25.5 | 377 | 24.5 | 371 | 24.1 |  | 0.91 (0.75,1.1) | --- | |
   12 | 394 | 27.4 | 361 | 25.1 | 338 | 23.5 | 345 | 24.0 |  | 0.86 (0.71,1.0) | --- | |
   9-11 | 171 | 15.7 | 166 | 15.2 | 361 | 33.1 | 393 | 36.0 |  | 1.1 (0.82,1.3) | --- | |
   0-8 | 46 | 16.7 | 60 | 21.7 | 71 | 25.7 | 99 | 35.9 |  | 2.1 (1.5,3.1) | --- | |
   Missing | 7 | 24.1 | 7 | 24.1 | 7 | 24.1 | 8 | 27.7 |  | --- | --- | |
Dietary Fat (% of daily calories) | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   ≤ 30% | 768 | 23.8 | 762 | 23.5 | 828 | 25.7 | 870 | 27.0 | <0.0001 | 1.0 | --- | |
   >30% | 685 | 26.6 | 690 | 26.7 | 624 | 24.2 | 582 | 22.5 |  | 0.75 (0.65,0.87) | --- | |
Pre-pregnancy BMI | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   Normal weight (18.5 < 25.0) | 67 | 21.3 | 81 | 25.8 | 82 | 26.1 | 84 | 26.8 | 0.6610 | 1.0 | --- | |
   Under weight (<18.5) | 813 | 25.9 | 775 | 24.7 | 783 | 25.0 | 765 | 24.4 |  | 1.3 (0.55,1.9) | --- | |
   Over weight (25.0 < 30.0) | 315 | 25.3 | 305 | 24.5 | 325 | 26.1 | 299 | 24.0 |  | 1.0 (0.84,1.2) | --- | |
   Obese (≥30.0) | 215 | 24.2 | 241 | 27.2 | 212 | 23.9 | 219 | 24.7 |  | 1.1 (0.88,1.3) | --- | |
   Missing | 43 | 18.9 | 50 | 21.9 | 50 | 21.9 | 85 | 37.3 |  | --- | --- | |
Folic acid containing supplements | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   No | 687 | 26.4 | 617 | 23.7 | 617 | 23.7 | 678 | 26.2 | 0.0070 | 1.0 | --- | |
   Yes | 758 | 23.9 | 828 | 26.0 | 827 | 26.0 | 765 | 24.1 |  | 1.0 (0.88,1.2) | --- | |
   Missing | 8 | 25.0 | 7 | 21.9 | 8 | 25.0 | 9 | 28.1 |  | --- | --- | |
Multivitamin use | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   No | 876 | 24.6 | 905 | 25.4 | 898 | 25.2 | 885 | 24.8 | 0.7780 | 1.0 | --- | |
   Yes | 568 | 25.6 | 546 | 24.6 | 548 | 24.7 | 558 | 25.1 |  | 0.97 (0.84,1.3) | --- | |
   Missing | 9 | 36.0 | 1 | 4.0 | 6 | 24.0 | 9 | 36.0 |  | --- | --- | |
Maternal age at conception (years) | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | Â | |
   20-24 | 409 | 30.5 | 328 | 24.5 | 306 | 22.9 | 296 | 22.1 | <0.0001 | 1.0 | --- | |
   <20 | 241 | 29.3 | 213 | 25.8 | 189 | 23.0 | 180 | 21.9 |  | 1.0 (0.80,1.3) | --- | |
   25-29 | 371 | 23.8 | 410 | 26.3 | 382 | 24.5 | 397 | 25.4 |  | 1.5 (1.2,1.8) | --- | |
   30-34 | 304 | 21.3 | 364 | 25.6 | 390 | 27.3 | 368 | 25.8 |  | 1.7 (1.4,2.1) | --- | |
   35+ | 128 | 19.4 | 137 | 20.7 | 185 | 28.0 | 211 | 31.9 |  | 2.3 (1.8,2.9) | --- |