Table 2 Clinical characteristics of women in the vaginal delivery group
Characteristics | Without PP history (n = 4438) | With PP history (n = 29) | P value |
|---|---|---|---|
Maternal age (years) | 30.39 ± 4.07 | 32.41 ± 4.32 | 0.42a |
  < 35 years | 3760 (84.7%) | 23 (79.3%) |  |
  ≥ 35 years | 678 (15.3%) | 6 (20.7%) |  |
Gestational age | 38.57 ± 2.3 | 37.45 ± 4.18 | < 0.05a |
  < 28 weeks | 55 (1.2%) | 1 (3.4%) |  |
 28–34 weeks | 56 (1.3%) | 3 (10.3%) |  |
 34–37 weeks | 194 (4.4%) | 1 (3.4%) |  |
  ≥ 37 weeks | 4130 (93.1%) | 24 (82.8%) |  |
Level of education | 0.067 | ||
 College | 2701 (60.9%) | 13 (44.8%) |  |
 Below college | 1629 (36.7%) | 14 (48.3%) |  |
 Unknown | 108 (2.4%) | 2 (6.9%) |  |
Mode of conception | < 0.05 | ||
 Natural | 4337 (97.7%) | 26 (89.7%) |  |
 ART | 101 (2.3%) | 3 (10.3%) |  |
Prior abortions | 0.991 | ||
 0 | 3222 (72.6%) | 21 (72.4%) |  |
 1 | 886 (20%) | 6 (20.7%) |  |
  ≥ 2 | 330 (7.4%) | 2 (6.9%) |  |
Prior deliveries | < 0.05 | ||
 1 | 3992 (90%) | 22 (75.9%) |  |
  ≥ 2 | 346 (10%) | 7 (24.1%) |  |
Sex of offspring | 0.783 | ||
 Male | 2334 (52.5%) | 18 (62.1%) |  |
 Female | 2104 (47.4%) | 11 (37.9%) |  |
Interval time | 3.23 ± 1.76 | 2.62 ± 1.47 | < 0.05 |