Table 5

Joint impact of daily volume and weekend delivery (model 3*), controlling for hospital-level factors

OutcomeLow/average-volume weekdayHigh-volume weekdayLow/average-volume weekendHigh-volume weekend
Model 3 (interaction model with fixed effects)
Maternal
 Obstetric infectionRef.1.03 (1.00 to 1.07)1.05 (1.01 to 1.09)1.02 (0.93 to 1.11)
 HaemorrhageRef.0.98 (0.95 to 1.01)1.01 (0.98 to 1.06)0.92 (0.85 to 0.98)
 Severe perineal lacerationRef.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 maternalRef.1.02 (1.00 to 1.04)1.10 (1.07 to 1.12)1.05 (1.00 to 1.10)
Neonatal
 Birth traumaRef.1.00 (0.97 to 1.04)0.99 (0.95 to 1.03)0.96 (0.89 to 1.05)
 Neonatal seizuresRef.1.34 (1.03 to 1.74)1.10 (0.82 to 1.48)0.95 (0.57 to 1.57)
 Apgar score <7Ref.1.04 (0.96 to 1.12)1.10 (1.02 to 1.20)1.21 (1.04 to 1.40)
 NICU admissionRef.1.00 (0.97 to 1.03)1.06 (1.02 to 1.10)1.09 (1.01 to 1.18)
 Neonatal deathRef.0.91 (0.78 to 1.06)1.02 (0.88 to 1.19)0.74 (0.48 to 1.15)
 Composite infantRef.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.