Table 4. Variable importance.
| Variables (attribute) | Variable importance from the random forest |
|---|---|
| BMI, delivery | 0.1426 |
| BMI, pregestational | 0.1215 |
| Age | 0.1211 |
| Parity | 0.0868 |
| BP, predelivery systolic | 0.0809 |
| BP, predelivery diastolic | 0.0763 |
| Twin | 0.0476 |
| Education | 0.0332 |
| Infant sex | 0.0331 |
| Prior preterm birth | 0.0290 |
| Medication history, progesterone | 0.0279 |
| Upper gastrointestinal tract symptom | 0.0274 |
| GERD | 0.0242 |
| Helicobacter pylori | 0.0151 |
| Region | 0.0139 |
| Medication history, calcium channel blocker | 0.0135 |
| Diabetes mellitus, gestational | 0.0130 |
| In vitro fertilisation | 0.0116 |
| Preeclampsia | 0.0113 |
| Myoma uteri | 0.0104 |
| Income | 0.0085 |
| Periodontitis | 0.0084 |
| Smoking | 0.0062 |
| Diabetes mellitus, type I | 0.0060 |
| Pelvic inflammatory disease history | 0.0057 |
| Drinking | 0.0043 |
| Hypertension, chronic | 0.0042 |
| Diabetes mellitus, type II | 0.0038 |
| Hypertension, gestational | 0.0030 |
| Medication history, benzodiazepine | 0.0028 |
| Medication history, nitrate | 0.0026 |
| Prior previa | 0.0022 |
| Adenomyosis | 0.0008 |
| Prior cone | 0.0006 |
| Medication history, sleeping pills | 0.0005 |
| Medication history, tricyclic antidepressant | 0.0000 |
BMI = body mass index; BP = blood pressure; GERD = gastroesophageal reflux disease.