Table 4.
Association Between Exposure to Nitrosatable Drugs Around the Time of Conceptiona and Spina Bifida, by Estimated Dietary Intake of Nitrites and Total Nitrites,b National Birth Defects Prevention Study, 1997–2005
| Dietary Intake (mg/day) and Type of Drug Exposure | Cases |
Controls |
Unadjusted ORc | 95% CI | Adjusted ORd | 95% CI | ||
| No. | % | No. | % | |||||
| Nitrites | ||||||||
| <1.27 | ||||||||
| No nitrosatable drug exposure | 168 | 82.8 | 1,743 | 82.3 | 1 | Referent | 1 | Referent |
| Secondary amines | 16 | 8.7 | 222 | 11.3 | 0.75 | 0.44, 1.27 | 0.80 | 0.47, 1.37 |
| Tertiary amines | 20 | 10.6 | 193 | 10.0 | 1.08 | 0.66, 1.75 | 1.14 | 0.69, 1.86 |
| 1.27–1.91 | ||||||||
| No nitrosatable drug exposure | 175 | 79.2 | 1,754 | 82.3 | 1 | Referent | 1 | Referent |
| Secondary amines | 26 | 12.9 | 220 | 11.1 | 1.19 | 0.77, 1.83 | 1.15 | 0.74, 1.80 |
| Tertiary amines | 28 | 13.8 | 177 | 9.2 | 1.59 | 1.03, 2.43 | 1.62 | 1.05, 2.50 |
| >1.91 | ||||||||
| No nitrosatable drug exposure | 209 | 82.3 | 1,797 | 84.3 | 1 | Referent | 1 | Referent |
| Secondary amines | 26 | 11.1 | 193 | 9.7 | 1.16 | 0.75, 1.79 | 1.38 | 0.88, 2.16 |
| Tertiary amines | 30 | 12.6 | 190 | 9.6 | 1.36 | 0.90, 2.05 | 1.72 | 1.12, 2.66 |
| Total nitritesb | ||||||||
| <3.02 | ||||||||
| No nitrosatable drug exposure | 177 | 80.5 | 1,753 | 82.7 | 1 | Referent | 1 | Referent |
| Secondary amines | 18 | 9.2 | 220 | 11.2 | 0.81 | 0.49, 1.34 | 0.82 | 0.49, 1.36 |
| Tertiary amines | 28 | 13.7 | 183 | 9.5 | 1.52 | 0.99, 2.32 | 1.57 | 1.02, 2.42 |
| 3.02–4.56 | ||||||||
| No nitrosatable drug exposure | 184 | 79.3 | 1,747 | 81.8 | 1 | Referent | 1 | Referent |
| Secondary amines | 28 | 13.2 | 233 | 11.8 | 1.14 | 0.75, 1.74 | 1.21 | 0.79, 1.87 |
| Tertiary amines | 31 | 14.4 | 206 | 10.6 | 1.43 | 0.95, 2.15 | 1.56 | 1.02, 2.37 |
| >4.56 | ||||||||
| No nitrosatable drug exposure | 187 | 84.2 | 1,789 | 84.4 | 1 | Referent | 1 | Referent |
| Secondary amines | 22 | 10.5 | 182 | 9.2 | 1.16 | 0.73, 1.85 | 1.31 | 0.81, 2.11 |
| Tertiary amines | 19 | 9.2 | 171 | 8.7 | 1.06 | 0.65, 1.75 | 1.20 | 0.72, 2.00 |
Abbreviations: CI, confidence interval; OR, odds ratio.
a
The period from 1 month before conception to 1 month after conception.
b
Total nitrites = daily dietary nitrite intake + 5% of daily nitrate intake.
c
Crude and adjusted odds ratios included only cases and controls for whom we had complete information on drug exposures and covariates.
d
Adjusted for maternal race/ethnicity, educational level, folic acid supplementation, and total energy intake.