Table 1 Maternal baseline characteristics and the first birth characteristics among women with previous SVD and those with previous CS and non-indicated CS
|  | previous SVD (n = 6240) | previous CS (n = 5422) | P- valuea | previous non-indicated CS (n = 1827) | P- valueb | |||
|---|---|---|---|---|---|---|---|---|
N | % | N | % | Â | N | % | ||
Baseline characteristics | ||||||||
 Birth place | ||||||||
  Shanghai | 4753 | 76.2% | 3991 | 73.6% | 0.001 | 1413 | 77.3% | 0.300 |
  Out of Shanghai | 1487 | 23.8% | 1431 | 26.4% |  | 414 | 22.7% |  |
 Race | ||||||||
  Han | 6164 | 98.8% | 5353 | 98.7% | 0.791 | 1812 | 99.2% | 0.158 |
  Minority | 76 | 1.2% | 69 | 1.3% |  | 15 | 0.8% |  |
 Insurance | ||||||||
  Public | 4239 | 67.9% | 3376 | 62.3% | < 0.001 | 1099 | 60.2% | < 0.001 |
  Self-pay | 2001 | 32.1% | 2046 | 37.7% |  | 728 | 39.8% |  |
 Marital status | ||||||||
  Married/cohabitating | 6158 | 99.7% | 5366 | 99.5% | 0.093 | 1802 | 99.3% | 0.007 |
  Not married/cohabitating | 17 | 0.3% | 25 | 0.5% |  | 13 | 0.7% |  |
 Age at the second delivery | ||||||||
  <25 years | 73 | 1.2% | 39 | 0.8% | < 0.001 | 10 | 0.5% | < 0.001 |
  25–29 years | 1152 | 18.5% | 739 | 13.6% |  | 228 | 12.5% |  |
  30–34 years | 3055 | 48.9% | 2727 | 50.3% |  | 917 | 50.2% |  |
  35–39 years | 1702 | 27.3% | 1693 | 31.2% |  | 585 | 32.0% |  |
   ≥ 40 years | 258 | 4.1% | 224 | 4.1% |  | 87 | 4.8% |  |
 Height (cm) | ||||||||
  <155 | 222 | 3.6% | 317 | 5.8% | < 0.001 | 91 | 5.0% | 0.001 |
  155–164.9 | 4013 | 64.3% | 3651 | 67.4% |  | 1206 | 66.0% |  |
  165–174.9 | 1935 | 31.0% | 1419 | 26.2% |  | 520 | 28.5% |  |
   ≥ 175 | 70 | 1.1% | 35 | 0.6% |  | 10 | 0.5% |  |
 Maternal BMI (Kg/m2) | ||||||||
  <18.5 | 550 | 8.8% | 405 | 7.5% | < 0.001 | 139 | 7.6% | < 0.001 |
  18.5–24.9 | 5313 | 85.2% | 4530 | 83.5% |  | 1507 | 82.5% |  |
  25–29.9 | 338 | 5.4% | 423 | 7.8% |  | 155 | 8.5% |  |
   ≥ 30 | 39 | 0.6% | 64 | 1.2% |  | 26 | 1.4% |  |
 Educational level (years) | ||||||||
   ≤ 9 | 266 | 4.4% | 205 | 3.9% | 0.042 | 35 | 2.0% | < 0.001 |
  10–12 | 494 | 8.2% | 469 | 9.0% |  | 130 | 7.4% |  |
  13–15 | 1205 | 20.1% | 1119 | 21.6% |  | 398 | 22.5% |  |
   ≥ 16 | 4049 | 67.3% | 3399 | 65.5% |  | 1203 | 68.1% |  |
 Gravidity | ||||||||
   ≤ 2 | 2984 | 47.8% | 2366 | 43.6% | < 0.001 | 825 | 45.2% | 0.045 |
   ≥ 3 | 3256 | 52.2% | 3056 | 56.4% |  | 1002 | 54.8% |  |
 Interpregnancy interval (years) | ||||||||
  <1 | 431 | 7.0% | 88 | 1.6% | < 0.001 | 29 | 1.6% | < 0.001 |
  1–3 | 1935 | 31.2% | 1350 | 25.0% |  | 446 | 24.5% |  |
  3–5 | 1357 | 21.9% | 1521 | 28.2% |  | 540 | 29.6% |  |
  5–10 | 1816 | 29.3% | 1957 | 36.2% |  | 665 | 36.5% |  |
   ≥ 10 | 657 | 10.6% | 485 | 9.0% |  | 142 | 7.8% |  |
First birth characteristics | ||||||||
 PIH | ||||||||
  Yes | 109 | 1.7% | 103 | 1.9% | 0.538 | 65 | 3.6% | < 0.001 |
  No | 6131 | 98.3% | 5319 | 98.1% |  | 1762 | 96.4% |  |
 PE | ||||||||
  Yes | 81 | 1.3% | 90 | 1.7% | 0.105 | 40 | 2.2% | 0.006 |
  No | 6159 | 98.7% | 5332 | 98.3% |  | 1787 | 97.8% |  |
 GDM | ||||||||
  Yes | 415 | 6.7% | 378 | 7.0% | 0.492 | 159 | 8.7% | 0.003 |
  No | 5825 | 93.3% | 5044 | 93.0% |  | 1668 | 91.3% |  |
 Stillbirths | ||||||||
  Yes | 61 | 1.0% | 10 | 0.2% | < 0.001 | 0 | 0.0% | < 0.001 |
  No | 6179 | 99.0% | 5412 | 99.8% |  | 1827 | 100.0% |  |
 LBW | ||||||||
  Yes | 144 | 2.3% | 144 | 2.7% | 0.227 | 26 | 1.4% | 0.021 |
  No | 6096 | 97.7% | 5278 | 97.3% |  | 1801 | 98.6% |  |
 Macrosomia | ||||||||
  Yes | 279 | 4.5% | 572 | 10.5% | < 0.001 | 211 | 11.5% | < 0.001 |
  No | 5961 | 95.5% | 4850 | 89.5% |  | 1616 | 88.5% |  |
 Preterm delivery | ||||||||
  Yes | 266 | 4.3% | 188 | 3.5% | 0.027 | 16 | 0.9% | < 0.001 |
  No | 5974 | 95.7% | 5234 | 96.5% |  | 1811 | 99.1% |  |