Table 1 Descriptive characteristics of the participants
Variable/Characteristic | Controls (n = 268) | CHDs cases (n = 245) | χ2 | P-values |
|---|---|---|---|---|
No. (%) | No. (%) | |||
Maternal age (years) | Â | Â | 1.067 | 0.302 |
< 35 | 234(87.31%) | 221(90.2%) |  |  |
≥ 35 | 34(12.69%) | 24(9.8%) |  |  |
Maternal ethnicity |  |  | 43.979 | < 0.001 |
Han | 259(96.64%) | 189(77.14%) | Â | Â |
Others | 9(3.36%) | 56(22.86%) | Â | Â |
Maternal education level |  |  | 63.325 | < 0.001 |
Junior school or lower | 37(13.81%) | 101(41.22%) | Â | Â |
High school | 42(15.67%) | 52(21.22%) | Â | Â |
College or higher | 189(70.52%) | 92(37.55%) | Â | Â |
Parental smoking or ETS exposurea | Â | Â | 6.524 | 0.011 |
Yes | 124(46.27%) | 141(57.55%) | Â | Â |
No | 144(53.73%) | 104(42.45%) | Â | Â |
Maternal alcohol consumptiona | Â | Â | 0.321 | 0.571 |
Yes | 41(15.3%) | 42(17.14%) | Â | Â |
No | 227(84.7%) | 203(82.86%) | Â | Â |
Parity |  |  | 15.727 | < 0.001 |
Nullipara | 143(53.36%) | 88(35.92%) | Â | Â |
Multipara | 125(46.64%) | 157(64.08%) | Â | Â |
Pre-pregnancy BMI (kg/m2) | Â | Â | 0.283 | 0.868 |
≤ 18.5 | 60(22.39%) | 56(22.86%) |  |  |
18.5–24 | 183(68.28%) | 163(66.53%) |  |  |
≥ 24 | 25(9.33%) | 26(10.61%) |  |  |
Folic acid supplementsa | Â | Â | 1.360 | 0.244 |
Yes | 226(84.33%) | 197(80.41%) | Â | Â |
No | 42(15.67%) | 48(19.59%) | Â | Â |