Table 3.
Association Between Exposure to Nitrosatable Drugs Around the time of Conceptiona and Anencephalyb, by Estimated Dietary Intake of Nitrites and Total Nitrites,c National Birth Defects Prevention Study, 1997–2005
| Dietary Intake (mg/day) and Type of Drug Exposure | Cases |
Controls |
Unadjusted ORd | 95% CI | Adjusted ORe | 95% CI | ||
| No. | % | No. | % | |||||
| Nitrites | ||||||||
| <1.27 | ||||||||
| No nitrosatable drug exposure | 78 | 86.7 | 1,743 | 82.3 | 1 | Referent | 1 | Referent |
| Secondary amines | 7 | 8.2 | 222 | 11.3 | 0.71 | 0.32, 1.55 | 0.77 | 0.35, 1.70 |
| Tertiary amines | 6 | 7.1 | 193 | 10.0 | 0.70 | 0.30, 1.62 | 0.77 | 0.33, 1.80 |
| 1.27–1.91 | ||||||||
| No nitrosatable drug exposure | 76 | 70.4 | 1,754 | 82.3 | 1 | Referent | 1 | Referent |
| Secondary amines | 16 | 17.4 | 220 | 11.1 | 1.68 | 0.96, 2.93 | 1.68 | 0.96, 2.97 |
| Tertiary amines | 23 | 23.2 | 177 | 9.2 | 3.00 | 1.84, 4.90 | 3.18 | 1.92, 5.27 |
| >1.91 | ||||||||
| No nitrosatable drug exposure | 105 | 80.8 | 1,797 | 84.3 | 1 | Referent | 1 | Referent |
| Secondary amines | 15 | 12.5 | 193 | 9.7 | 1.33 | 0.76, 2.33 | 1.67 | 0.93, 2.99 |
| Tertiary amines | 16 | 13.2 | 190 | 9.6 | 1.44 | 0.83, 2.49 | 1.98 | 1.11, 3.51 |
| Total nitrites | ||||||||
| <3.02 | ||||||||
| No nitrosatable drug exposure | 92 | 82.9 | 1,753 | 82.7 | 1 | Referent | 1 | Referent |
| Secondary amines | 10 | 9.8 | 220 | 11.2 | 0.87 | 0.44, 1.69 | 0.93 | 0.47, 1.83 |
| Tertiary amines | 10 | 9.8 | 183 | 9.5 | 1.04 | 0.53, 2.04 | 1.16 | 0.59, 2.29 |
| 3.02–4.56 | ||||||||
| No nitrosatable drug exposure | 77 | 76.2 | 1,747 | 81.8 | 1 | Referent | 1 | Referent |
| Secondary amines | 13 | 14.4 | 233 | 11.8 | 1.27 | 0.69, 2.31 | 1.38 | 0.74, 2.57 |
| Tertiary amines | 17 | 18.1 | 206 | 10.6 | 1.87 | 1.09, 3.23 | 2.19 | 1.25, 3.86 |
| >4.56 | ||||||||
| No nitrosatable drug exposure | 90 | 77.6 | 1,789 | 84.4 | 1 | Referent | 1 | Referent |
| Secondary amines | 15 | 14.3 | 182 | 9.2 | 1.64 | 0.93, 2.89 | 1.86 | 1.03, 3.36 |
| Tertiary amines | 18 | 16.7 | 171 | 8.7 | 2.09 | 1.23, 3.55 | 2.51 | 1.45, 4.37 |
Abbreviations: CI, confidence interval; OR, odds ratio.
a
The period from 1 month before conception to 1 month after conception.
b
This category included craniorachischisis.
c
Total nitrites = daily dietary nitrite intake + 5% of daily nitrate intake.
d
Crude and adjusted odds ratios included only cases and controls for whom we had complete information on drug exposures and covariates.
e
Adjusted for maternal race/ethnicity, educational level, folic acid supplementation, and total energy intake.