Table 1.
Crude odds ratios (cOR) for maternal characteristics and exposures among case and control mothers, National Birth Defects Prevention Study, 1997–2007
| Cases (n = 301) |
Controls (n = 8135) |
||||
|---|---|---|---|---|---|
| Maternal characteristics | N | % | N | % | cOR [95%CI] |
| Age (years) | |||||
| <20 | 30 | (10.0) | 848 | (10.4) | 1.09 [0.71, 1.68) |
| 20–24 | 76 | (25.3) | 1876 | (23.1) | 1.25 [0.90, 1.73] |
| 25–29 | 73 | (24.3) | 2246 | (27.6) | 1.00 [Reference] |
| ≥30 | 122 | (40.5) | 3165 | (38.9) | 1.19 [0.88, 1.59] |
| Race/ethnicity | |||||
| White, non-Hispanic | 172 | (57.1) | 4841 | (59.5) | 1.00 [Reference] |
| Black, non-Hispanic | 46 | (15.3) | 910 | (11.2) | 1,42 [1.02, 1.98] |
| Hispanic | 60 | (19.9) | 1862 | (22.9) | 0.91 [0.67, 1.22] |
| Other | 23 | (7.6) | 519 | (6.4) | 1.25 [0.80, 1.95] |
| Missing | 0 | 3 | (0.1) | – | |
| Education (years) | |||||
| <12 | 43 | (14.3) | 1383 | (17.0) | 1.00 [Reference] |
| ≥12 | 258 | (85.7) | 6722 | (82.6) | 1.23 [0.89, 1.71] |
| Missing | 0 | 30 | (0.4) | – | |
| Preconception BMIa | |||||
| <18.5 | 17 | (5.7) | 433 | (5.3) | 1.30 [0.78, 2.17] |
| 18.5–24.9 | 131 | (43.5) | 4325 | (53.2) | 1.00 [Reference] |
| ≥25.0 | 142 | (47.2) | 3044 | (37.4) | 1.54 [1.21, 1.96] |
| Missing | 11 | (3.7) | 333 | (4.1) | – |
| Previous pregnancy | |||||
| 0 | 103 | (34.2) | 2434 | (29.9) | 1.00 [Reference] |
| >1 | 198 | (65.8) | 5700 | (70.1) | 0.82 [0.64, 1.05] |
| Missing | 0 | 1 | (0.01) | – | |
| Fever | |||||
| No | 296 | (98.3) | 8000 | (98.3) | 1.00 [Reference] |
| Yes | 4 | (1.3) | 94 | (1.2) | 1.15 [0.42, 3.15] |
| Missing | 1 | (0.3) | 41 | (0.5) | – |
| Substance abuse | |||||
| No | 237 | (78.7) | 6240 | (76.7) | 1.00 [Reference] |
| Yes | 14 | (4.7) | 331 | (4.1) | 1.11 [0.64, 1.93] |
| Missing | 50 | (16.6) | 1564 | (19.2) | – |
| Alcohol Use | |||||
| No | 161 | (53.5) | 5095 | (62.6) | 1.00 [Reference] |
| Yes | 140 | (46.5) | 3004 | (36.9) | 1.48 [1.17, 1.86] |
| Missing | 0 | 36 | (0.4) | – | |
| Folic acid supplements | |||||
| None | 39 | (13.0) | 1016 | (12.5) | 1.00 [Reference] |
| Periconceptionb | 261 | (86.7) | 7013 | (86.2) | 0.97 [0.69, 1.37] |
| Missing | 1 | (0.3) | 106 | (1.3) | – |
| Gestational diabetes | |||||
| No | 284 | (94.4) | 7746 | (95.2) | 1.00 [Reference] |
| Yes | 16 | (5.3) | 341 | (4.2) | 1.28 [0.77, 2.14] |
| Missing | 1 | (0.3) | 48 | (0.6) | – |
| Paternal age (years) | |||||
| <20 | 10 | (3.3) | 378 | (4.7) | 0.69 [0.35, 1.33] |
| 20–24 | 50 | (16.6) | 1401 | (17.2) | 0.92 [0.64, 1.32] |
| 25–29 | 80 | (26.6) | 2070 | (25.5) | 1.00 [Reference] |
| ≥30 | 149 | (49.5) | 3971 | (48.8) | 0.97 [0.74, 1.28] |
| Missing | 12 | (4.0) | 315 | (3.9). | – |
| Time to interview (months) | |||||
| <12 | 196 | (65.1) | 6054 | (74.4) | 1.00 [Reference] |
| ≥12 | 104 | (34.6) | 2054 | (25.3) | 1.56 [1.23, 1.99] |
| Missing | 1 | (0.3) | 27 | (0.3) | – |
| Centre | |||||
| Arkansas | 38 | (12.6) | 1039 | (12.8) | 1.00 [Reference] |
| California | 45 | (15.0) | 985 | (12.1) | 1.25 [0.80, 1.94] |
| Georgia | 42 | (14.0) | 853 | (10.5) | 1.35 [0.86, 2.11] |
| Iowa | 25 | (8.3) | 900 | (11.1) | 0.76 [0.46, 1.27] |
| Massachusetts | 36 | (12.0) | 1003 | (12.3) | 0.98 [0.62, 1.56] |
| New Jersey | 27 | (9.0) | 568 | (7.0) | 1.30 [0.79, 2.15] |
| New York | 20 | (6.6) | 704 | (8.7) | 0.78 [0.45, 1.35] |
| North Carolina | 10 | (3.3) | 553 | (6.8) | 0.50 [0.25, 1.00] |
| Texas | 37 | (12.3) | 935 | (11.5) | 1.08 [0.68, 1.72] |
| Utah | 21 | (7.0) | 595 | (7.3) | 0.97 [0.56, 1.66] |
| Cigarette smoke exposure | |||||
| None | 186 | (61.8) | 5528 | (68.0) | 1.00 [Reference] |
| Maternal only | 21 | (7.0) | 609 | (7.5) | 1.03 [0.65, 1.62] |
| Second-hand smoke only | 56 | (18.6) | 1103 | (13.6) | 1,51 [1.11, 2.05] |
| Maternal and second-hand | 38 | (12.6) | 880 | (10.8) | 1.28 [0.90, 1.83] |
| Missing | 0 | 15 | (0.2) | – | |
a
BMI = body mass index in kg/m2.
b
Includes women reporting multivitamins or prenatal vitamins with folic acid or folic acid alone.