Objective To describe the trend and risk factors for severe intraventricular haemorrhage (IVH) among infants <32 weeks gestation.
Design Population-based cohort study.
Setting Australia and New Zealand.
Patients All preterm infants <32 weeks gestation in the Australian and New Zealand Neonatal Network (ANZNN) from 1995 to 2012.
Interventions Comparison of IVH incidence between 6-year epochs.
Main outcome measures Overall IVH and severe IVH incidence.
Results A total of 60 068 infants were included, and overall survival to discharge increased from 89% to 93% over the three epochs. As the percentage of infants with IVH decreased from 23.6% to 21.3% and 21.4% (p<0.001) from epoch 1 to 3, respectively, fewer survivors had severe IVH (4.0%, 3.3% and 2.8%, respectively, p<0.001). Over time, there were fewer antenatal complications, higher antenatal steroid usage and more caesarean-section births. Fewer infants were intubated at birth, had low 5 min Apgar score, had sepsis or pneumothorax needing drainage. Adjusted for perinatal confounders, there was significant reduction in odds of severe IVH from epoch 1 to 3 (adjusted OR (AOR) 0.8, 95% CI 0.7 to 0.9). Factors associated with development of severe IVH include no antenatal steroids (AOR 1.7, 95% CI 1.5 to 1.9), male (AOR 1.3, 95% CI 1.2 to 1.4), 5 min Apgar score <7 (AOR 2.0, 95% CI 1.9 to 2.2), intubated at birth (AOR 2.0, 95% CI 1.8 to 2.2), extremely low gestational age (AOR 4.0, 95% CI 3.7 to 4.4), outborn (AOR 1.6, 95% CI 1.5 to 1.8) and vaginal delivery (AOR 1.4, 95% CI 1.3 to 1.6).
Conclusions Along with increased survival among infants born <32 weeks gestation, the incidence of severe IVH has decreased over the 18 years, especially in the most recent period. This coincided with reduction in rates of risk factors for severe IVH development.
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Contributors KTY, RT, KL were involved in the conception and design of the work; acquisition, analysis and interpretation of the data for the manuscript and initial drafting of the manuscript. They had full access to all data in the study. KTY had the final responsibility for submission for publication. SC was involved in the acquisition, analysis and interpretation of the data for the work. SB, RH, WT-M were involved in the interpretation of the data for the manuscript.
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.
Ethics approval The South Eastern Sydney Local Health District Human Research Ethics Committee approved this study (HREC ref: 14/208).
Provenance and peer review Not commissioned; externally peer reviewed.
Collaborators Advisory Council Members of ANZNN (*denotes ANZNN Executive) Australia: Peter Marshall (Flinders Medical Centre, SA), Peter Schmidt (Gold Coast University Hospital, QLD), Paul Craven, Koert de Waal* (John Hunter Children’s Hospital, NSW), Karen Simmer, Andy Gill*, Jane Pillow* (King Edward Memorial and Princess Margaret Hospitals, WA), Jacqueline Stack (Liverpool Hospital, NSW), Pita Birch (Mater Mother’s Hospital, QLD), Dan Casalaz, Jim Holberton* (Mercy Hospital for Women, VIC), Alice Stewart (Monash Medical Centre, VIC), Lucy Cooke* (Neonatal Retrieval Emergency Service Southern Queensland, QLD), Lyn Downe (Nepean Hospital, NSW), Michael Stewart (Paediatric Infant Perinatal Emergency Retrieval, VIC), Andrew Berry (NSW Newborn & paediatric Emergency Transport Service), Rod Hunt (Royal Children’s Hospital, VIC), Charles Kilburn (Royal Darwin Hospital, NT), Tony De Paoli (Royal Hobart Hospital, TAS), Kei Lui* (Royal Hospital for Women, NSW), Mary Paradisis (Royal North Shore Hospital, NSW), Ingrid Rieger, (Royal Prince Alfred Hospital, NSW), Pieter Koorts (Royal Women’s Hospital, QLD), Carl Kuschel, Lex Doyle, (Royal Women’s Hospital, VIC), Andrew Numa (Sydney Children’s Hospital, NSW), Hazel Carlisle (The Canberra Hospital, ACT), Nadia Badawi, Christine Jorgensen* (The Children’s Hospital at Westmead, NSW), Guan Koh (The Townsville Hospital, QLD), Jonathan Davis (Western Australia Neonatal Transport Service), Melissa Luig (Westmead Hospital, NSW), Chad Andersen (Women’s & Children’s Hospital, SA). New Zealand: Adrienne Lynn (Christchurch Women’s Hospital), Brian Darlow (Christchurch School of Medicine), Liza Edmonds (Dunedin Hospital), Lindsay Mildenhall (Middlemore Hospital), Mariam Buksh, Malcolm Battin* (Auckland City Hospital), David Bourchier (Waikato Hospital), Vaughan Richardson, Fiona Dineen* (Wellington Women’s Hospital). ANZNN Executive not members of hospitals contributing data: Georgina Chambers* (National Perinatal Statistics and Epidemiology Unit, University of New South Wales); Victor Samuel Rajadurai* (KK Women’s and Children’s Hospital, Singapore); Barbara Bajuk* (NSW Pregnancy and Newborn Services Network), Jutta van den Boom* (Waitemata DHB).
Patient consent for publication Not required.