Adverse outcomes of labour in public and private hospitals in Australia

To the Editor: Robson and colleagues found higher crude odds of perinatal death in public hospitals — an unsurprising finding, given the maternal demographics in the public system.1 However, after taking into account known risk factors for poor perinatal outcome by “adjusting for the potentially confounding variables available in the NPDC [National Perinatal Data Collection]”, the authors found that the odds ratio actually went up — implying that the pregnancies of mothers in the private system are higher risk. This is implausible.