Table 2

 Relation between postmenstrual age at discharge, characteristics of the infant, and region of care

Coefficient (PMAD in weeks)SE95% CIp Value
The adjusted postmenstrual age at discharge (PMAD) is shown together with the 95% confidence interval (CI). All coefficients are adjusted for the clustered nature of the data (n  =  4216; 143 patients with missing covariates were excluded).
Constant32.931.05(30.87 to 35.00)<0.001
Region of care
    California−0.560.19(−0.93 to −0.19)0.003
    Massachusetts−0.130.15(−0.43 to 0.17)0.385
    United Kingdom0
Mother received antenatal steroids
    Yes−0.0050.05(−0.10 to 0.09)0.920
Infant delivered by caesarean section
    Yes0.070.05(−0.02 to 0.16)0.121
Gestational age at delivery (weeks)0.110.03(0.06 to 0.16)<0.001
Sex of infant
    Male0.150.05(0.05 to 0.24)0.003
Size for gestation (birthweight z- score)−0.700.04(−0.78 to −0.62)<0.001
Apgar score at 5 min−0.060.04(−0.13 to 0.01)0.103
Infant received mechanical ventilation
    Yes0.750.06(0.64 to 0.87)<0.001