Table 2.
Crude primary c-section ORs by all variables and adjusted ORs by the variables included in the full and the parsimonious model
| VARIABLE | Total n. | % of total | Crude OR | p | Full Model | Parsimonious model | ||
| Adj. OR | p | Adj. OR | p | |||||
| Variables from mothers' discharge records | ||||||||
| AGE, yrs | ||||||||
| 29–33 | 5.648 | 37.17 | ref. | ref. | ref. | |||
| <= 17 | 35 | 0.23 | 0.6 | 0.001 | 0.5 | 0.005 | 0.5 | 0.002 |
| 18–20 | 276 | 1.82 | 0.7 | < 0.001 | 0.8 | 0.006 | 0.7 | < 0.001 |
| 21–24 | 1.051 | 6.92 | 0.8 | < 0.001 | 0.8 | < 0.001 | 0.8 | < 0.001 |
| 25–28 | 2.657 | 17.48 | 0.9 | < 0.001 | 0.9 | 0.004 | 0.9 | < 0.001 |
| 34–38 | 4.203 | 27.66 | 1.2 | < 0.001 | 1.1 | < 0.001 | 1.2 | < 0.001 |
| >=39 | 1.327 | 8.73 | 1.7 | < 0.001 | 1.7 | < 0.001 | 1.8 | < 0.001 |
| Marital status | ||||||||
| Married | 6.700 | 44.09 | ref. | ref. | ref. | |||
| Divorced/separated | 190 | 1.25 | 1.3 | 0.001 | 1.2 | 0.082 | 1.2 | 0.162 |
| Not declared | 1.124 | 7.40 | 1.0 | 0.224 | 1.1 | 0.048 | 1.1 | 0.011 |
| Single | 2.948 | 19.40 | 1.1 | < 0.001 | 1.2 | < 0.001 | 1.2 | < 0.001 |
| Widow | 13 | 0.09 | 1.0 | 0.916 | 1.0 | 0.906 | 1.0 | 0.866 |
| Citizenship | ||||||||
| Italian | 12.908 | 84.94 | ref. | ref. | ||||
| Non developing countries excluding Italy | 2.193 | 14.43 | 0.9 | 0.489 | 0.8 | 0.103 | ||
| Developing countries | 96 | 0.63 | 0.8 | < 0.001 | 0.8 | < 0.001 | ||
| Region of residence: | ||||||||
| RER | 14.016 | 92.23 | 1.0 | ref. | ||||
| Other region | 1.181 | 7.77 | 0.8 | < 0.001 | 0.7 | < 0.001 | ||
| Diabetes | 239 | 1.57 | 3.9 | < 0.001 | 3.1 | < 0.001 | ||
| Hypertension | 505 | 3.32 | 3.4 | < 0.001 | 3.8 | < 0.001 | ||
| Lung disease | 44 | 0.29 | 7.3 | < 0.001 | 5.7 | < 0.001 | ||
| HIV | 38 | 0.25 | 19.9 | < 0.001 | 28.3 | < 0.001 | ||
| Other severe co-morbid illness of the mother | 187 | 1.23 | 4.4 | < 0.001 | 5.1 | < 0.001 | ||
| Eclampsia or pre-eclampsia | 870 | 5.72 | 9.0 | < 0.001 | 9.1 | < 0.001 | 8.5 | < 0.001 |
| Antepartum hemorrhage/abruptio placentae/placenta previa/ | 673 | 4.43 | 57.0 | < 0.001 | 75.1 | < 0.001 | 62.0 | < 0.001 |
| Polyhydramnios | 85 | 0.56 | 5.6 | < 0.001 | 4.3 | < 0.001 | ||
| Oligohydramnios | 946 | 6.22 | 2.2 | < 0.001 | 2.9 | < 0.001 | ||
| Premature rupture of membranes | 1.563 | 10.28 | 0.7 | < 0.001 | - | - | ||
| Other problems of the amnios | 25 | 0.16 | 9.8 | < 0.001 | 10.2 | < 0.001 | ||
| Cord prolapse | 33 | 0.22 | 52.0 | < 0.001 | 70.3 | < 0.001 | ||
| Abortion threads/assisted fecundation/supervision of high risk pregnancy | 89 | 0.59 | 6.5 | < 0.001 | 4.3 | < 0.001 | ||
| Pre-term delivery | 355 | 2.34 | 2.2 | < 0.001 | - | - | ||
| Post-term delivery | 424 | 2.73 | 0.8 | 0.001 | 1.4 | < 0.001 | ||
| Malposition and malpresentation of fetus | 3.093 | 20.35 | 124.9 | < 0.001 | 155.5 | < 0.001 | 145.9 | < 0.001 |
| Fetopelvic disproportion/excessive development of the infant | 772 | 5.08 | 8.6 | < 0.001 | 14.1 | < 0.001 | 13.1 | < 0.001 |
| Fetal abnormality | 127 | 0.84 | 5.1 | < 0.001 | 3.9 | < 0.001 | ||
| Rh-isoimmunization | 138 | 0.91 | 0.7 | < 0.001 | - | - | ||
| Variables from neonatal discharge record | ||||||||
| Infant birth weight (grams) | ||||||||
| > 2500 | 12.753 | 83.92 | ref. | ref. | ref. | |||
| 550–1499 | 353 | 2.32 | 18.6 | < 0.001 | 5.7 | < 0.001 | 15.0 | < 0.001 |
| 1500–2499 | 2.040 | 13.42 | 6.1 | < 0.001 | 2.6 | < 0.001 | 5.5 | < 0.001 |
| Congenital malformation | 781 | 5.14 | 2.0 | < 0.001 | 1.5 | < 0.001 | ||
| Post-maturity or macrosomia | 132 | 0.87 | 1.8 | < 0.001 | - | - | ||
| Variables from both neonatal and maternal discharge records | ||||||||
| Intrauterine growth retardation | 953 | 6.27 | 4.77 | < 0.001 | 2.2 | < 0.001 | ||
| Multiple pregnancy | 1.323 | 8.71 | 17.29 | < 0.001 | 9.8 | < 0.001 | ||