Objectives To compare mortality and serious morbidity rates between outborn and inborn livebirths at 22–27 weeks' gestation.
Design Population-based cohort study.
Setting Victoria, Australia.
Patients Livebirths at 22–27 weeks' gestation free of major malformations in 2010–2011.
Interventions Outcome data for outborn (born outside a tertiary perinatal centre) infants compared with inborn (born in a tertiary perinatal centre) infants were analysed by logistic regression, adjusted for gestational age, birth weight and sex.
Main outcome measures Infant mortality and serious morbidity rates to hospital discharge.
Results 541 livebirths free of major malformations were recorded. By 1 year, 49 (58%) outborns and 140 (31%) inborns died (adjusted OR (aOR) 2.78, 95% CI 1.52 to 5.09, p=0.001). In total, 445 infants were admitted to neonatal intensive care unit (NICU); 93 died by 1 year (14/49 outborns and 79/396 inborns), (aOR 1.75, 95% CI 0.87 to 3.55, p=0.12). There were no significant differences in rates of necrotising enterocolitis, intraventricular haemorrhage, retinopathy of prematurity, bronchopulmonary dysplasia (BPD) or the combined outcome of death or BPD in outborn infants compared with inborn infants. Outborns had an increased risk of cystic periventricular leukomalacia (cPVL) compared with inborns (12.2% vs 2.8%, respectively; aOR 5.34, 95% CI 1.84 to 15.54, p=0.002).
Conclusions Mortality rates remained higher for outborn livebirths at 22–27 weeks' gestation compared with inborn peers in 2010–2011. Outborn infants admitted to NICU did not have substantially different rates of mortality or serious morbidity compared with inborns, with the exception of cPVL. Longer-term health consequences of outborn birth before 28 weeks' gestation need to be determined.
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Correction notice This paper has been amended since it was published Online First. An error was introduced into the legend of table 1 by the production office. The words ‘livebirths at’ were inadvertently introduced. These words have now been deleted.
Twitter Follow Rosemarie Boland at @roseandtoby
Contributors RAB designed the study, wrote the ethics, collected, cleaned and analysed the data and wrote the draft manuscript. LWD, JAD and PGD supervised and contributed to all stages of the study design and statistical analysis and edited the manuscript. The content has not been reproduced from another source, other than the points of text that are referenced as part of the literature review. Each author has reviewed the manuscript and approved the submission of this revised version. The authors take full responsibility for the manuscript.
Funding RAB was the recipient of the Felix Meyer Faculty Research Scholarship from the Faculty of Medicine, Dentistry and Health Sciences at the University of Melbourne. Her PhD research was also supported with funding from a National Health and Medical Research Council (NHMRC) Centre for Research Excellence in Newborn Medicine at the Murdoch Childrens Research Institute (ID 1060733). RAB currently holds a Postdoctoral Fellowship, funded by the Murdoch Childrens Research Institute. JAD and PGD are funded by the NHMRC: JAD holds an Early Career Fellowship (ID 1059111); PGD holds a Practitioner Fellowship (ID 1012686).
Competing interests None declared.
Ethics approval The following Human Research and Ethics Committees approved the study: (1) CCOPMM. Victorian Government Department of Health and Human Services. Study ID: RR13-31. (2) Royal Children's Hospital, Parkville, Victoria, including the PIPER service. ID 31124A. (3) Mercy Health, Heidelberg, Victoria. Study ID: R11/28. (4) Southern Health: Clayton, Victoria. Study ID: 11320Q. (5) Royal Women's Hospital, Parkville, Victoria. Study ID: 11/06.
Provenance and peer review Not commissioned; externally peer reviewed.
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