Table 1 Baseline characteristics of participants between case group and control group
Case group n = 587 | Control group n = 1180 | t/χ2 /Z value | P value | |
|---|---|---|---|---|
Maternal age, n (%) | 28.24 ± 5.02 | 29.00 ± 4.27 | -3.790 | < 0.001a |
Maternal BMI | 20.73 ± 2.54 | 20.41 ± 2.04 | -2.413 | 0.016 a |
Education, n (%) | ||||
Primary school and below | 8 (1.36) | 5 (0.42) | 171.408 | < 0.001 |
Junior middle school | 27 (4.60) | 111 (9.41) | ||
High middle school | 227 (38.67) | 147 (12.46) | ||
Above high middle school | 325 (55.37) | 917 (77.71) | ||
Ethnicity, n (%) | ||||
Han | 572 (97.44) | 1172 (99.32) | 10.755 | 0.001 |
Other | 15 (2.56) | 8 (0.68) | ||
Residence, n (%) | ||||
Rural | 390 (66.44) | 391 (33.14) | 176.287 | < 0.001 |
Urban | 197 (33.56) | 789 (66.86) | ||
Family wealth index, n (%) | ||||
Low | 309 (52.64) | 325 (27.54) | 117.732 | < 0.001 |
Medium | 161 (27.43) | 391 (33.14) | ||
High | 117 (19.93) | 464 (39.32) | ||
Parity, n (%) | ||||
0 | 360 (61.33) | 947 (80.25) | 83.038 | < 0.001 |
1 | 200 (34.07) | 223 (18.90) | ||
≥ 2 | 27 (4.60) | 10 (0.85) | ||
Abortion history, n (%) | ||||
Yes | 206 (35.09) | 425 (36.02) | 0.146 | 0.703 |
No | 381 (64.91) | 755 (63.98) | ||
Family history of birth defects, n (%) | ||||
Yes | 58 (9.88) | 61 (5.17) | 13.852 | < 0.001 |
No | 529 (90.12) | 1119 (94.83) | ||
Active or passive smoking, n (%) | ||||
Yes | 345 (58.77) | 678 (57.46) | 41.379 | < 0.001 |
No | 242 (41.23) | 502 (42.54) | ||
Drinking, n (%) | ||||
Yes | 18 (3.07) | 8 (0.68) | 15.425 | < 0.001 |
No | 569 (96.93) | 1172 (99.32) | ||
Folic acid supplement, n (%) | ||||
Yes | 450 (76.66) | 1020 (86.44) | 26.812 | < 0.001 |
No | 137 (23.34) | 160 (13.56) | ||
Fever, n (%) | ||||
Yes | 53 (9.03) | 78 (6.61) | 3.341 | 0.068 |
No | 534 (90.97) | 1102 (93.39) | ||
Taking medicine, n (%) | ||||
Yes | 129 (21.98) | 161 (13.64) | 19.837 | < 0.001 |
No | 458 (78.02) | 1019 (86.36) | ||
GDM, n (%) | ||||
Yes | 16 (2.73) | 44 (3.73) | 1.202 | 0.273 |
No | 571 (97.27) | 1136 (96.27) | ||
TORCH infections, n (%) | ||||
Yes | 6 (1.02) | 2 (0.17) | 4.573 | 0.032 b |
No | 581 (98.98) | 1178 (99.83) | ||
Industries exposure, n (%) | ||||
Yes | 73 (12.44) | 42 (3.56) | 50.765 | < 0.001 |
No | 514 (87.56) | 1138 (96.44) |