Table 4.
Logistics regression to identify potential risk factors for preterm birth before 34 weeks (N = 3,288).
| Variables | PTB before 34 weeks (n = 617) | after 34 weeks (n = 2,671) | P-value | Multivariate analysis | ||
|---|---|---|---|---|---|---|
| OR | 95% CI | P-value | ||||
| Age (y)* | 0.004 | 0.003 | ||||
| <25 | 52 (8.4%) | 134 (5.0%) | 1.888 | 1.307–2.728 | 0.001 | |
| 25–34 | 439 (71.2%) | 1,989 (74.5%) | Ref. | |||
| ≥35 | 126 (20.4%) | 548 (20.5%) | 1.107 | 0.870–1.409 | 0.408 | |
| Parity | 0.513 | |||||
| Nulli | 391 (63.4%) | 1,731 (64.8%) | ||||
| Pluri | 226 (36.6%) | 940 (35.2%) | ||||
| PTB histroy | 1.000 | |||||
| Yes | 13 (2.1%) | 55 (2.1%) | ||||
| No | 604 (97.9%) | 2,616 (97.9%) | ||||
| Conception* | 0.171 | |||||
| Natural | 387 (62.7%) | 1,595 (59.7%) | ||||
| ART | 230 (37.3%) | 1,076 (40.3%) | ||||
| Chorionicity* | <0.001 | |||||
| Dichorionic | 337 (54.6%) | 2,097 (78.5%) | Ref. | |||
| Monochorionic | 280 (45.4%) | 574 (21.5%) | 2.865 | 2.344–3.501 | <0.001 | |
| Height (cm)* | 0.002 | 0.054 | ||||
| <160 | 204 (35.4%) | 768 (29.9%) | 1.069 | 0.868–1.316 | 0.532 | |
| 160–169 | 362 (62.8%) | 1,701 (66.1%) | Ref. | |||
| ≥170 | 10 (1.7%) | 103 (4.0%) | 0.400 | 0.181–0.883 | 0.023 | |
| Pre BMI (kg/m2) | 0.345 | |||||
| <18.5 | 92 (17.3%) | 397 (16.2%) | ||||
| 18.5–23.9 | 336 (63.3%) | 1,634 (66.7%) | ||||
| 24.0–27.9 | 85 (16.0%) | 329 (13.4%) | ||||
| ≥28.0 | 18 (3.4%) | 91 (3.7%) | ||||
| Weight Gain (kg)* | <0.001 | <0.001 | ||||
| <10 | 74 (13.7%) | 115 (4.7%) | 3.100 | 2.198–4.372 | <0.001 | |
| 10–14.9 | 127 (23.6%) | 469 (19.0%) | 1.215 | 0.939–1.571 | 0.138 | |
| 15–19 | 199 (36.9%) | 946 (38.3%) | Ref. | |||
| ≥20 | 139 (25.8%) | 938 (38.0%) | 0.667 | 0.524–0.849 | 0.001 | |
| HDP* | 0.171 | |||||
| No | 528 (85.6%) | 2,344 (87.8%) | ||||
| GH | 17 (2.8%) | 88 (3.3%) | ||||
| HTN | 2 (0.3%) | 5 (0.2%) | ||||
| PE | 70 (11.3%) | 234 (8.8%) | ||||
| ICP* | 0.117 | |||||
| Yes | 30 (4.9%) | 176 (6.6%) | ||||
| No | 587 (95.1%) | 2,495 (93.4%) | ||||
*
Factors assigned to multivariate logistic regression analysis.
Ref., reference; PTB, preterm birth; ART, assistant reproductive technology; BMI, body mass index; HDP, hypertensive disorders of pregnancy; HTN, hypertension; GH, gestational hypertension; PE, preeclampsia; ICP, intrahepatic cholestasis of pregnancy.