Table 1 The description of characteristics by CHD Cases vs. Controls (n, %)
| Â | All CHD | Simple CHD | Complex CHD | VSD | TOF | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Cases (n=524) | Controls (n=262) | p value | Cases (n=262) | Controls (n=262) | p value | Cases (n=262) | Controls (n=262) | p value | Cases (n=60) | Controls (n=262) | p value | Cases (n=97) | Controls (n=262) | p value | |
Demographic and obstetric characteristics | |||||||||||||||
 Maternal ethnic |  |  | 0.236 |  |  | 0.243 |  |  | 0.337 |  |  | 1.000 |  |  | 0.716 |
  Han | 501,95.6 | 255, 97.3 |  | 250, 95.4 | 255, 97.3 |  | 251, 95.8 | 255, 97.3 |  | 58, 96.7 | 255, 97.3 |  | 93, 95.9 | 255, 97.3 |  |
  Other | 30,4.4 | 7, 2.7 |  | 12, 4.6 | 7, 2.7 |  | 11, 4.2 | 7, 2.7 |  | 2, 3.3 | 7, 2.7 |  | 4, 4.1 | 7, 2.7 |  |
 Maternal age at delivery |  |  | 0.543 |  |  | 1.000 |  |  | 0.302 |  |  | 0.235 |  |  | 0.391 |
  <35 years old | 473,90.3 | 240, 91.6 |  | 240, 91.6 | 240, 91.6 |  | 233, 88.9 | 240, 91.6 |  | 52, 86.7 | 240, 91.6 |  | 86, 88.7 | 240, 91.6 |  |
  ≥35 years old | 51,9.7 | 22, 8.4 |  | 22, 8.4 | 22, 8.4 |  | 29, 11.1 | 22, 8.4 |  | 8, 13.3 | 22, 8.4 |  | 11, 11.3 | 22, 8.4 |  |
 Maternal education |  |  | <0.001 |  |  | 0.014 |  |  | <0.001 |  |  | 0.113 |  |  | <0.001 |
  Middle school and below | 184,35.1 | 58, 22.1 |  | 83, 31.7 | 58, 22.1 |  | 101, 38.5 | 58, 22.1 |  | 21, 35.0 | 58, 22.1 |  | 40, 41.2 | 58, 22.1 |  |
  High school | 117,22.3 | 48, 18.3 |  | 55, 21.0 | 48, 18.3 |  | 62, 23.7 | 48, 18.3 |  | 9, 15.0 | 48, 18.3 |  | 24, 24.7 | 48, 18.3 |  |
  College and above | 223,42.6 | 156, 59.5 |  | 124, 47.3 | 156, 59.5 |  | 99, 37.8 | 156, 59.5 |  | 30, 50.0 | 156, 59.5 |  | 33, 34.0 | 156, 59.5 |  |
 Marital status |  |  | 0.613 |  |  | 1.000 |  |  | 0.279 |  |  | 0.588 |  |  | 0.785 |
  Married | 511,97.5 | 257, 98.1 |  | 258, 98.5 | 257, 98.1 |  | 253, 96.6 | 257, 98.1 |  | 60, 100.0 | 257, 98.0 |  | 94, 96.9 | 257, 98.1 |  |
  Unmarried/divorced/widowed | 13,2.5 | 5, 1.9 |  | 4, 1.5 | 5, 1.9 |  | 9, 3.4 | 5, 1.9 |  | 0, 0 | 5, 1.9 |  | 3, 3.1 | 5, 1.9 |  |
 Residence |  |  | <0.001 |  |  | <0.001 |  |  | <0.001 |  |  | 0.017 |  |  | <0.001 |
  Urban | 209,39.9 | 166, 63.4 |  | 110, 42.0 | 166, 63.4 |  | 99, 37.8 | 166, 63.4 |  | 28, 46.7 | 166, 63.4 |  | 37, 38.1 | 166, 63.4 |  |
  Suburban /rural | 315,60.1 | 96, 36.6 |  | 152, 58.0 | 96, 36.6 |  | 163, 62.2 | 96, 36.6 |  | 32, 53.3 | 96, 36.6 |  | 60, 61.9 | 96, 36.6 |  |
 Maternal prepregnancy obesity |  |  | 0.523 |  |  | 0.432 |  |  | 0.108 |  |  | 1.000 |  |  | 0.104 |
  Yes | 23,4.4 | 9, 3.4 |  | 6, 2.3 | 9, 3.4 |  | 17, 6.5 | 9, 3.4 |  | 2, 3.3 | 9, 3.4 |  | 8, 8.2 | 9, 3.4 |  |
  No | 501,95.6 | 253, 96.6 |  | 256, 97.7 | 253, 96.6 |  | 245, 93.5 | 253, 96.6 |  | 58, 96.7 | 253, 96.6 |  | 89, 91.8 | 253, 96.6 |  |
 Multiple births |  |  | 0.857 |  |  | 0.178 |  |  | 0.381 |  |  | 0.594 |  |  | 0.067 |
  Yes | 44,8.4 | 23, 8.8 |  | 15, 5.7 | 23, 8.8 |  | 29, 11.1 | 2, 8.8 |  | 4, 6.7 | 23, 8.8 |  | 15, 15.5 | 2, 8.8 |  |
  No | 480,91.6 | 239, 91.2 |  | 247, 94.3 | 239, 91.2 |  | 233, 88.9 | 239, 91.2 |  | 56, 93.3 | 239, 91.2 |  | 82, 84.5 | 239, 91.2 |  |
 Infant gender |  |  | 0.014 |  |  | <0.001 |  |  | 0.470 |  |  | 0.281 |  |  | 0.885 |
  Male | 288,55.0 | 168, 64.1 |  | 128, 48.8 | 168, 64.1 |  | 160, 61.1 | 168, 64.1 |  | 34, 56.7 | 168, 64.1 |  | 63, 64.9 | 168, 64.1 |  |
  Female | 236,45.0 | 94, 35.9 |  | 134, 51.1 | 94, 35.9 |  | 102, 38.9 | 94, 35.9 |  | 26, 43.3 | 94, 35.9 |  | 34, 35.1 | 94, 35.9 |  |
 Family history of CHD |  |  | 0.024 |  |  | 0.005 |  |  | 0.218 |  |  | 0.054 |  |  | 0.292 |
  Yes | 31,5.9 | 6, 2.3 |  | 20, 7.6 | 6, 2.3 |  | 11, 4.2 | 6, 2.3 |  | 5, 8.3 | 6, 2.3 |  | 5, 5.2 | 6, 2.3 |  |
  No | 493,94.1 | 256, 97.7 |  | 242, 92.4 | 256, 97.7 |  | 251, 95.8 | 256, 97.7 |  | 55, 91.7 | 256, 97.7 |  | 92, 94.8 | 256, 97.7 |  |
Maternal health indicators and behaviors | |||||||||||||||
 Diabetes/hypertension |  |  | 0.488 |  |  | 0.179 |  |  | 0.793 |  |  | 0.430 |  |  | 0.716 |
  Yes | 10,1.9 | 7, 2.7 |  | 2, 0.8 | 7, 2.7 |  | 8, 3.1 | 7, 2.7 |  | 0, 0 | 7, 2.7 |  | 4, 4.1 | 7, 2.7 |  |
  No | 514,98.1 | 255, 97.3 |  | 260, 99.2 | 255, 97.3 |  | 254, 96.9 | 255, 97.3 |  | 60, 100.0 | 255, 97.3 |  | 93, 95.9 | 255, 97.3 |  |
 Folic acid supplementation |  |  | 0.001 |  |  | 0.044 |  |  | <0.001 |  |  | 0.017 |  |  | 0.007 |
  Yes | 390,74.4 | 222, 84.7 |  | 204, 77.9 | 222, 84.7 |  | 186, 71.0 | 222, 84.7 |  | 43, 71.7 | 222, 84.7 |  | 70, 72.2 | 222, 84.7 |  |
  No | 134,25.6 | 40, 15.3 |  | 58, 22.1 | 40, 15.3 |  | 76, 29.0 | 40, 15.3 |  | 17, 28.3 | 40, 15.3 |  | 27, 27.8 | 40, 15.3 |  |
 Smoking/drinking |  |  | 0.305 |  |  | 0.883 |  |  | 0.065 |  |  | 0.688 |  |  | 0.027 |
  Yes | 65,12.4 | 26, 9.9 |  | 25, 9.5 | 26, 9.9 |  | 40, 15.3 | 26, 9.9 |  | 7, 11.7 | 26, 9.9 |  | 18, 18.6 | 26, 9.9 |  |
  No | 459,87.6 | 236, 90.1 |  | 237, 90.5 | 236, 90.1 |  | 222, 84.7 | 236, 90.1 |  | 53, 88.3 | 236, 90.1 |  | 79, 81.4 | 236, 90.1 |  |