- Demographic characteristics of the study participants.
| Characteristics | Total n=2942 | Preterm n=1471 | Term n=1471 | t/P |
|---|---|---|---|---|
| Maternal age* | 30.20±5.202 | 30.50±5.589 | 29.89±4.765 | <0.001 |
| <20 | 56 (1.9) | 40 (2.7) | 16 (1.1) | <0.001 |
| 20-34 | 2252 (76.5) | 1075 (73.1) | 1177 (80.0) | |
| ≥35 | 634 (21.6) | 356 (24.2) | 278 (18.9) | |
| Parity | ||||
| Unipara | 1448 (49.2) | 658 (44.7) | 790 (53.7) | <0.001 |
| Multipara | 1494 (50.8) | 813 (55.3) | 681 (46.3) | |
| Race | ||||
| Han | 2777 (94.4) | 1373 (93.3) | 1404 (95.4) | 0.013 |
| Others | 165 (5.6) | 98 (6.7) | 67 (4.6) | |
| Maternal Education | ||||
| Middle school or below | 787 (26.7) | 467 (31.7) | 320 (21.8) | <0.001 |
| High school | 688 (23.4) | 377 (5.6) | 311 (21.1) | |
| University or above | 1467 (49.9) | 627 (42.6) | 840 (57.1) | |
| Residence during pregnancy | ||||
| City | 1482 (50.4) | 650 (44.2) | 832 (56.6) | <0.001 |
| Small town | 1062 (36.1) | 568 (38.6) | 494 (33.6) | |
| Countryside | 398 (13.5) | 253 (17.2) | 145 (9.8) | |
| Family income monthly per person (yuan) | ||||
| <2,000 | 224 (7.6) | 141 (9.6) | 83 (5.6) | <0.001 |
| 2,000-10,000 | 2115 (71.9) | 1053 (71.6) | 1062 (72.2) | |
| >10,000 | 603 (20.5) | 277 (18.8) | 326 (22.2) | |
Values are presented as numbers and percentages (%).
↵* mean±standard deviation