Objective We compared mortality and morbidity of inborn versus outborn very preterm infants <32 weeks’ gestation in Western Australia (WA) between 2005 and 2018.
Design Retrospective cohort study.
Patients Infants <32 weeks’ gestation who were born in WA.
Main outcome measures Mortality was assessed as death before discharge home from the tertiary neonatal intensive care unit. Short-term morbidities included combined brain injury (intracranial haemorrhage grade ≥3 and cystic periventricular leukomalacia) and other major neonatal outcomes. Developmental assessments at age 2, 3 and 5 years were evaluated. We performed multivariable logistic regression analysis of outborn status on outcomes, controlling for gestational age, birth weight z-score, sex and multiple birth.
Results A total of 4974 infants were born in WA between 22 and 32 weeks’ gestation between 2005 and 2018 of which 4237 (89.6%) were inborn and 443 (10.4%) were outborn. Overall mortality to discharge was higher in outborn infants (20.5% (91/443) vs 7.4% (314/4237); adjusted OR (aOR) 2.44, 95% CI 1.60 to 3.70, p<0.001). Outborn infants had higher rates of combined brain injury than those inborn (10.7% (41/384) vs 6.0% (246/4115); aOR 1.98, 95% CI 1.37 to 2.86), p<0.001). No difference in up to 5-year developmental measures was detected. Follow-up data were available for 65% of outborn and 79% of inborn infants.
Conclusions Outborn preterm infants <32 weeks in WA had increased odds of mortality and combined brain injury than those inborn. Developmental outcomes up to 5 years were similar between groups. Loss to follow-up may have impacted the long-term comparison.
- intensive care units, neonatal
- child development
- infant development
Data availability statement
Data are available on reasonable request.
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Contributors JWD designed the original concept, interpreted results, drafted and revised the manuscript and approved for final submission. JWD acts as guarantor for this work. CES designed the original concept, the acquisition of data, interpreted results, revised the manuscript and approved for final submission. EAN assisted in the design of the original concept, acquisition and analysis of the data, revision of the manuscript and approval of final submission. TS assisted in designing the original concept, interpreting the result, revising the manuscript and approval for final submission. AG assisted in designing the original concept, interpreting the result, revising the manuscript and approval for final submission. MS designed the original concept, interpreted results, drafted and revised the manuscript and approved for final submission.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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