| Crude OR (95% CI) | Adjusted OR for all covariates (95% CI) | Adjusted OR for confounders only (95% CI) | |
| Asthma yes/no | 1.35 (1.08 to 1.67) | 0.95 (0.74 to 1.22) | 0.93 (0.75 to 1.17) |
| Age | |||
| <18 | 1.19 (0.73 to 1.91) | 0.91 (0.49 to 1.69) | † |
| 18–34 | Reference (–) | Reference (–) | |
| ⩾35 | 1.59 (1.16 to 2.18) | 1.40 (0.97 to 2.01) | |
| Social assistance yes/no | 1.32 (1.05 to 1.67) | 0.80 (0.60 to 1.06) | † |
| Level of education | |||
| ⩽11 | 1.25 (0.98 to 1.59) | 0.95 (0.72 to 1.26) | † |
| ⩾12 | Reference (–) | Reference (–) | – |
| Missing | 4.49 (3.39 to 5.95) | 2.44 (1.73 to 3.45) | |
| Parity | |||
| 1 | Reference (–) | Reference | † |
| ⩾2 | 1.13 (0.89 to 1.43) | 1.12 (0.86 to 1.47) | |
| PIH yes/no | 1.24 (0.82 to 1.89) | 0.53 (0.32 to 0.87) | † |
| Diabetes mellitus yes/no | 1.97 (1.07 to 3.60) | 1.58 (0.79 to 3.18) | † |
| Gestational diabetes yes/no | 0.80 (0.51 to 1.26) | 0.72 (0.43 to 1.21) | † |
| Placental abruption yes/no | 7.33 (5.59 to 9.62) | 1.75 (1.28 to 2.40) | † |
| Infection of amniotic cavity yes/no | 3.74 (2.80 to 4.99) | 1.92 (1.37 to 2.68) | † |
| Cord around neck yes/no | 0.74 (0.55 to 1.01) | 0.86 (0.61 to 1.21) | † |
| Birth weight ⩽2500/>2500 g | 34.75 (27.58 to 43.79) | 10.55 (7.40 to 15.15) | 9.11 (6.61 to 15.55) |
| Gestational age at birth <37/⩾37 weeks | 30.62 (24.27 to 38.63) | 6.24 (4.37 to 8.90) | 7.07 (5.12 to 9.77) |
PIH, pregnancy-induced hypertension.
†Not a confounder variable.