Table 1.
Characteristics of patients with or without iatrogenic preterm birth and univariable analysis in both datasets
| Characteristic | Training Dataset | Validation Dataset | |||
|---|---|---|---|---|---|
| IPTB = 0(n = 1283) | IPTB = 1(n = 283) | P | IPTB = 0(n = 615) | IPTB = 1(n = 134) | |
| Age, No. (%) | 0.866* | ||||
| ≤ 35 | 991 (82.04) | 217 (17.96) | 477 (82.10) | 104 (17.90) | |
| >35 | 292 (81.56) | 66 (18.44) | 318 (82.14) | 30 (17.86) | |
| Parity, No. (%) | |||||
| ≤1 (reference) | 1219 (83.04) | 249 (16.96) | 585 (83.21) | 118 (16.79) | |
| 2 | 59 (67.82) | 28 (32.18) | < 0.0001* | 28 (65.12) | 15 (34.88) |
| ≥ 3 | 5 (45.45) | 6 (54.55) | 0.004* | 2 (66.67) | 1 (33.3) |
| Myomectomy, No. (%) | 0.866 | ||||
| No | 1249 (81.90) | 276 (18.10) | 598 (81.98) | 132 (18.02) | |
| Yes | 34 (82.93) | 7 (17.07) | 17 (89.47) | 2 (10.53) | |
| Dysmenorrhea, No. (%) | 0.583 | ||||
| No | 950 (81.62) | 214 (18.38) | 463 (82.53) | 98 (17.47) | |
| Yes | 333 (82.84) | 69 (17.16) | 152 (80.85) | 36 (19.15) | |
| IPI, No. (%) | |||||
| 13to < 24 months (reference) | 133 (90.48) | 14 (9.52) | 0.002* | 54 (85.71) | 9 (14.29) |
| 0 to < 12 months | 15 (65.22) | 8 (34.78) | 9 (75.00) | 3 (25.00) | |
| 25 to < 60 months | 489 (83.02) | 100 (16.98) | 0.028* | 234 (86.99) | 35 (13.01) |
| ≥ 60 months | 646 (80.05) | 161 (19.95) | 0.003* | 318 (78.52) | 87 (21.48) |
| Conception method, No.(%) | 0.746 | ||||
| Normal | 1276 (81.95) | 281 (18.05) | 614 (82.31) | 132 (17.69) | |
| IVF-ET | 7 (77.78) | 2 (22.22) | 1 (33.33) | 2 (66.67) | |
| number of vaginal bleeding during pregnancy, No. (%) | < 0.0001* | ||||
| 0 | 1182 (84.13) | 223 (15.87) | 559 (85.74) | 93 (14.26) | |
| 1 | 85 (70.83) | 35 (29.17) | 44 (66.67) | 22 (33.33) | |
| 2 | 13 (44.83) | 16 (55.17) | 9 (40.91) | 13 (59.09) | |
| ≥ 3 | 3 (25.00) | 9 (75.00) | 3 (33.33) | 6 (66.67) | |
| Regularity of prenatal examination, No. (%) | 0.024* | ||||
| Yes | 984 (83.18) | 199 (16.82) | 470 (82.75) | 98 (17.25) | |
| No | 299 (78.07) | 84 (21.93) | 145 (80.11) | 36 (19.89) | |
| Foetal position, No. (%) | |||||
| Cephalic presentation (reference) | 1200 (83.22) | 242 (16.78) | 576 (83.24) | 116 (16.76) | |
| Breech presentation | 68 (68.69) | 31 (31.31) | < 0.0001* | 30 (83.33) | 6 (16.67) |
| Transverse presentation | 15 (60.00) | 10 (40.00) | 0.004* | 9 (42.86) | 12 (57.14) |
| GDM, No. (%) | 0.412 | ||||
| No | 1034 (82.32) | 222 (17.68) | 530 (82.94) | 109 (17.06) | |
| Yes | 249 (80.32) | 61 (19.68) | 85 (77.27) | 25 (22.73) | |
| Hypertension in pregnancy, No. (%) | < 0.0001* | ||||
| No | 1215 (85.56) | 205 (14.44) | 581 (84.94) | 103 (15.06) | |
| Yes | 68 (46.58) | 78 (53.42) | 34 (52.31) | 31 (47.69) | |
| Placental previa, No. (%) | < 0.0001* | ||||
| No | 1159 (85.54) | 196 (14.46) | 556 (87.70) | 78 (12.30) | |
| Yes | 124 (58.77) | 87 (41.23) | 59 (51.30) | 56 (48.70) | |
| Height (interquartile range) | 162 (160,165) | 161 (160,165) | 0.018* | 162 (160.165) | 162 (160.165) |
| Weight (interquartile range) | 72 (66,79) | 70 (65,80) | 0.585 | 71 (65,78) | 70 (65,78) |
Abbreviations: IPI interpregnancy interval, IPTB iatrogenic preterm birth, GDM gestational diabetes mellitus