Table 2 Descriptive statistics of dietary nitrate, nitrite, and nitrosamine intake and neural tube defects in offspring
| Â | Â | Â | Â | N (%) | |||
|---|---|---|---|---|---|---|---|
|  |  Outcome | N | Mean (SD) | Quartile 1 | Quartile 2 | Quartile 3 | Quartile 4 |
Nitrate (mg/day) | Â | Â | Â | Â | Â | Â | |
| Â | Anencephaly | 319 | 48.02 (32.99) | 90 (28.2) | 84 (26.3) | 65 (20.4) | 80 (25.1) |
| Â | Spina bifida | 658 | 49.83 (43.40) | 179 (27.2) | 168 (25.5) | 172 (26.1) | 139 (21.1) |
| Â | Encephalocele | 127 | 49.75 (36.88) | 35 (27.6) | 28 (22.0) | 37 (29.1) | 27 (21.3) |
Total Nitrite (mg/day) | Â | Â | Â | Â | Â | Â | |
| Â | Anencephaly | 319 | 1.88 (0.99) | 74 (23.2) | 63 (19.7) | 86 (27.0) | 96 (30.1) |
| Â | Spina bifida | 662 | 1.85 (1.05) | 157 (23.7) | 153 (23.1) | 165 (24.9) | 187 (28.2) |
| Â | Encephalocele | 127 | 1.84 (1.04) | 32 (25.2) | 31 (24.4) | 28 (22.0) | 36 (28.3) |
Animal Nitrite (mg/day) | Â | Â | Â | Â | Â | Â | |
| Â | Anencephaly | 320 | 1.15 (0.70) | 71 (22.2) | 71 (22.2) | 89 (27.8) | 89 (27.8) |
| Â | Spina bifida | 673 | 1.14 (0.79) | 157 (23.3) | 166 (24.7) | 180 (26.7) | 170 (25.3) |
| Â | Encephalocele | 128 | 1.20 (0.89) | 37 (28.9) | 23 (18.0) | 31 (24.2) | 37 (28.9) |
Plant Nitrite (mg/day) | Â | Â | Â | Â | Â | Â | |
| Â | Anencephaly | 319 | 0.74 (0.51) | 76 (23.8) | 84 (26.3) | 65 (20.4) | 94 (29.5) |
| Â | Spina bifida | 666 | 0.72 (0.49) | 170 (25.5) | 162 (24.3) | 138 (20.7) | 196 (29.4) |
| Â | Encephalocele | 129 | 0.66 (0.37) | 29 (22.5) | 31 (24.0) | 38 (29.5) | 31 (24.0) |
Nitrosamine (μg/day) |  |  |  |  |  |  | |
| Â | Anencephaly | 315 | 0.53 (0.30) | 77 (24.4) | 77 (24.4) | 84 (26.7) | 77 (24.4) |
| Â | Spina bifida | 664 | 0.55 (0.34) | 181 (27.3) | 150 (22.6) | 157 (23.6) | 176 (26.5) |
| Â | Encephalocele | 127 | 0.52 (0.32) | 34 (26.8) | 34 (26.8) | 26 (20.5) | 33 (26.0) |