Joint impact of daily volume and weekend delivery (model 3*), controlling for hospital-level factors
| Outcome | Low/average-volume weekday | High-volume weekday | Low/average-volume weekend | High-volume weekend |
|---|---|---|---|---|
| Model 3 (interaction model with fixed effects) | ||||
| Maternal | ||||
| Obstetric infection | Ref. | 1.03 (1.00 to 1.07) | 1.05 (1.01 to 1.09) | 1.02 (0.93 to 1.11) |
| Haemorrhage | Ref. | 0.98 (0.95 to 1.01) | 1.01 (0.98 to 1.06) | 0.92 (0.85 to 0.98) |
| Severe perineal laceration | Ref. | 0.99 (0.95 to 1.03) | 1.09 (1.05 to 1.14) | 1.03 (0.93 to 1.13) |
| Prolonged LOS† | Ref. | 1.06 (1.03 to 1.09) | 1.18 (1.14 to 1.22) | 1.25 (1.17 to 1.34) |
| Composite maternal | Ref. | 1.02 (1.00 to 1.04) | 1.10 (1.07 to 1.12) | 1.05 (1.00 to 1.10) |
| Neonatal | ||||
| Birth trauma | Ref. | 1.00 (0.97 to 1.04) | 0.99 (0.95 to 1.03) | 0.96 (0.89 to 1.05) |
| Neonatal seizures | Ref. | 1.34 (1.03 to 1.74) | 1.10 (0.82 to 1.48) | 0.95 (0.57 to 1.57) |
| Apgar score <7 | Ref. | 1.04 (0.96 to 1.12) | 1.10 (1.02 to 1.20) | 1.21 (1.04 to 1.40) |
| NICU admission | Ref. | 1.00 (0.97 to 1.03) | 1.06 (1.02 to 1.10) | 1.09 (1.01 to 1.18) |
| Neonatal death | Ref. | 0.91 (0.78 to 1.06) | 1.02 (0.88 to 1.19) | 0.74 (0.48 to 1.15) |
| Composite infant | Ref. | 1.00 (0.98 to 1.02) | 1.02 (0.99 to 1.05) | 1.04 (0.97 to 1.11) |
Bold typeface indicates p<0.05.
*Results are OR (95% CI); model controlled for maternal race/ethnicity, advanced maternal age, education, parity, insurance status and prenatal care. Models included hospital fixed-effects and estimated robust SEs accounting for hospital-level clustering.
†Prolonged LOS defined as LOS >3 days for vaginal deliveries and >5 days for caesarean deliveries.
LOS, length of stay; NICU, neonatal intensive care unit.