Table 1.
Characteristics of the case and control participants.
| Variables/Characteristic | Cases | Controls | χ 2 | P-values |
|---|---|---|---|---|
| No.(%) | No.(%) | |||
| Maternal age (yrs)a | 4.096 | 0.129 | ||
| <25 | 99(27.7) | 58(21.5) | ||
| 25–34 | 211(59.1) | 166(61.5) | ||
| ≥35 | 47(13.2) | 46(17.0) | ||
| Gestational weeka | 103.038 | <0.001 | ||
| <19 | 13(3.6) | 88(32.6) | ||
| 20–25 | 194(54.3) | 126(46.7) | ||
| 26–31 | 109(30.5) | 42(15.6) | ||
| ≥32 | 41(11.5) | 14(5.2) | ||
| Housing renovationb | 0.766 | 0.381 | ||
| Yes | 79(22.1) | 52(19.3) | ||
| No | 278(77.9) | 218(80.7) | ||
| Factory or landfill nearbyb | 0.460 | 0.498 | ||
| Yes | 56(15.7) | 37(13.7) | ||
| No | 298(83.5) | 230(85.2) | ||
| Cooking at homeb | 13.021 | 0.001 | ||
| Often | 203(56.9) | 122(45.2) | ||
| Never | 76(21.3) | 91(33.7) | ||
| Occasional | 75(21.0) | 54(20.0) | ||
| Parental smoking or ETS exposureb | 1.758 | 0.185 | ||
| Yes | 223(62.5) | 155(57.4) | ||
| No | 133(37.3) | 115(42.6) | ||
| Maternal alcohol consumptionb | 10.671 | 0.005 | ||
| Often | 6(1.7) | 8(3.0) | ||
| Occasional | 55(15.4) | 68(25.2) | ||
| Never | 293(82.1) | 194(71.9) | ||
| Folic acid supplementsb | 4.057 | 0.044 | ||
| Yes | 297(83.2) | 240(88.9) | ||
| No | 60(16.8) | 30(11.1) |
aUsing base data in following multivariate analysis as continuous variables.
bThe exposure was defined from the 3 months before pregnancy to the first trimester.