Variables | 18–24 (n = 2711) | 25–29 (5524) | 30–34 (n = 1751) | ≥35 (220) | P |
---|---|---|---|---|---|
Gravidity |  |  |  |  | < 0.05 |
 2 | 1212 (44.7%) | 2804 (50.8%) | 925 (52.8%) | 79 (35.9%) |  |
 3 | 829 (30.6%) | 1606 (29.1%) | 477 (27.2%) | 58 (26.4%) |  |
  ≥ 4 | 670 (24.7%) | 1114 (20.2%) | 349 (19.9%) | 83 (37.7%) |  |
Parity |  |  |  |  | < 0.05 |
 1 | 2626 (96.9%) | 5397 (97.7%) | 1663 (95%) | 178 (80.9%) |  |
 2 | 73 (2.7%) | 115 (2.1%) | 77 (4.4%) | 36 (16.4%) |  |
  ≥ 3 | 12 (0.4%) | 12 (0.2%) | 11 (0.6%) | 6 (2.7%) |  |
Age at second CD | 29 (27,33) | 33 (31,36) | 36 (35,38) | 40 (38,42) | < 0.05 |
BMI (kg/m2) |  |  |  |  | < 0.05 |
  < 18.5 | 266 (9.8%) | 381 (6.9%) | 88 (5%) | 7 (3.2%) |  |
 18.5–24.9 | 1812 (66.8%) | 3783 (68.5%) | 1208 (69%) | 153 (69.5%) |  |
 25–29.9 | 538 (19.8%) | 1200 (21.7%) | 394 (22.5%) | 54 (24.5%) |  |
≥30 | 95 (3.5%) | 160 (2.9%) | 61 (3.5%) | 6 (2.7%) |  |
Nationality |  |  |  |  | < 0.05 |
 Han | 2673 (98.6%) | 5414 (98%) | 1710 (97.7%) | 208 (94.5%) |  |
 Others | 38 (1.4%) | 110 (2%) | 41 (2.3%) | 12 (5.5%) |  |
Interval months | 84 (53,120) | 72 (48,108) | 60 (40,84) | 48 (32.25,60.75) | < 0.05 |
ART | 72 (2.7%) | 100 (1.8%) | 71 (4.1%) | 14 (6.4%) | < 0.05 |
Source |  |  |  |  | < 0.05 |
 Hospital | 2126 (78.4%) | 4626 (83.7%) | 1492 (85.2%) | 185 (84.1%) |  |
 Referral | 585 (21.6%) | 898 (16.3%) | 259 (14.8%) | 35 (15.9%) |  |
 Gestational weeks | 39 (37,39) | 39 (38,39) | 39 (38,39) | 39 (37.25,39) | < 0.05 |
Sex | Â | Â | Â | Â | 0.951 |
 Male | 1477 (54.5%) | 3047 (55.2%) | 960 (54.8%) | 121 (55%) |  |
 Female | 1234 (45.5%) | 2477 (44.8%) | 791 (45.2%) | 99 (45%) |  |