Table 1.
Infant and maternal characteristics of spina bifida and anencephaly cases and controls, National Birth Defects Prevention Study, 1997–2007
| Spina Bifidaa (N=836) | Anencephalya (N=403) | Controlsa (N=8,494) | ||||||
|---|---|---|---|---|---|---|---|---|
|
| ||||||||
| Exposure | N | (%) | P-valueb | N | (%) | P-valueb | N | (%) |
| Infant factors: | ||||||||
| Sex | ||||||||
| Male | 414 | (50.1) | 0.69 | 163 | (45.2) | 0.03 | 4,314 | (50.8) |
| Female | 412 | (49.9) | 198 | (54.8) | 4,172 | (49.2) | ||
| Family history of NTDsc | ||||||||
| Yes | 19 | (2.3) | <0.001 | 10 | (2.5) | <0.001 | 32 | (0.4) |
| No | 817 | (97.7) | 393 | (97.5) | 8,462 | (99.6) | ||
| Maternal factors: | ||||||||
| Race/ethnicity | ||||||||
| Non-Hispanic White | 451 | (54.1) | <0.001 | 194 | (48.4) | <0.001 | 4,958 | (58.6) |
| Non-Hispanic Black | 65 | (7.8) | 28 | (7.0) | 935 | (11.0) | ||
| Hispanic | 265 | (31.8) | 144 | (35.9) | 1,918 | (22.7) | ||
| Other | 53 | (6.4) | 35 | (8.7) | 653 | (7.7) | ||
| BMI (kg/m2) | ||||||||
| Underweight (<18.5) | 28 | (3.6) | <0.001 | 24 | (6.4) | 0.30 | 438 | (5.4) |
| Normal (18.5–24.9) | 356 | (46.0) | 191 | (50.8) | 4,474 | (55.1) | ||
| Overweight (25.0–29.9) | 185 | (23.9) | 87 | (23.1) | 1,854 | (22.8) | ||
| Obese (≥30) | 205 | (26.5) | 74 | (19.7) | 1,360 | (16.7) | ||
| Folic acid supplementationd,e | ||||||||
| Yes | 409 | (49.1) | 0.36 | 208 | (51.6) | 0.73 | 4,293 | (50.7) |
| No | 424 | (50.9) | 195 | (48.4) | 4,167 | (49.3) | ||
| Low dietary folate intake (daily μg) | ||||||||
| Quartile 4 (>720.5) | 193 | (23.3) | 0.06 | 92 | (22.9) | <0.001 | 2,107 | (25.0) |
| Quartile 3 (496.0–720.5) | 201 | (24.3) | 75 | (18.7) | 2,106 | (25.0) | ||
| Quartile 2 (333.7–495.9) | 202 | (24.4) | 103 | (25.6) | 2,107 | (25.0) | ||
| Quartile 1(≤333.6) | 232 | (28.0) | 132 | (32.8) | 2,107 | (25.0) | ||
| Anticonvulsant usee | ||||||||
| Yes | 16 | (1.9) | <0.001 | 6 | (1.5) | 0.14 | 65 | (0.8) |
| No | 816 | (98.1) | 393 | (98.5) | 8,369 | (99.2) | ||
| Diabetes before index pregnancy | ||||||||
| Yes | 3 | (0.4) | 0.63 | 8 | (2.0) | 0.005 | 51 | (0.6) |
| No | 831 | (99.6) | 395 | (98.0) | 8,423 | (99.4) | ||
| Gestational diabetes during index pregnancy | ||||||||
| Yes | 43 | (5.2) | 0.13 | 13 | (3.2) | 0.41 | 343 | (4.0) |
| No | 791 | (94.8) | 390 | (96.8) | 8,131 | (96.0) | ||
| Hot tub or sauna usee | ||||||||
| Yes | 40 | (4.9) | 0.25 | 24 | (6.1) | 0.84 | 488 | (5.9) |
| No | 780 | (95.1) | 370 | (93.9) | 7,852 | (94.1) | ||
a
Characteristic totals may not equal case group totals due to missing data
b
P-value from chi-square test (or Fisher exact test when an expected cell count was <5) of the comparison with controls
c
In first or second-degree relative
d
Any use of folic acid, multivitamin, or prenatal vitamin supplementation
e
During the month before pregnancy and the first month of pregnancy (B1-P1)