- The ANZIC Influenza Investigators and Australasian Maternity Outcomes Surveillance System
- Correspondence to: I Seppelt, Department of Intensive Care Medicine, Nepean Hospital, PO Box 63, Penrith, NSW 2751, Sydney, Australia
- Accepted 22 February 2010
Objective To describe the epidemiology of 2009 A/H1N1 influenza in critically ill pregnant women.
Design Population based cohort study.
Setting All intensive care units in Australia and New Zealand.
Participants All women with 2009 H1N1 influenza who were pregnant or recently post partum and admitted to an intensive care unit in Australia or New Zealand between 1 June and 31 August 2009.
Main outcome measures Maternal and neonatal mortality and morbidity.
Results 64 pregnant or postpartum women admitted to an intensive care unit had confirmed 2009 H1N1 influenza. Compared with non-pregnant women of childbearing age, pregnant or postpartum women with 2009 H1N1 influenza were at increased risk of admission to an intensive care unit (relative risk 7.4, 95% confidence interval 5.5 to 10.0). This risk was 13-fold greater (13.2, 9.6 to 18.3) for women at 20 or more weeks’ gestation. At the time of admission to an intensive care unit, 22 women (34%) were post partum and two had miscarried. 14 women (22%) gave birth during their stay in intensive care and 26 (41%) were discharged from an intensive care unit with ongoing pregnancy. All subsequently delivered. 44 women (69%) were mechanically ventilated. Of these, nine (14%) were treated with extracorporeal membrane oxygenation. Seven women (11%) died. Of 60 births after 20 weeks’ gestation, four were stillbirths and three were infant deaths. 22 (39%) of the liveborn babies were preterm and 32 (57%) were admitted to a neonatal intensive care unit. Of 20 babies tested, two were positive for the 2009 H1N1 virus.
Conclusions Pregnancy is a risk factor for critical illness related to 2009 H1N1 influenza, which causes maternal and neonatal morbidity and mortality.
The Australian and New Zealand Intensive Care (ANZIC) Influenza Investigators are a collaboration of the ANZIC Society Clinical Trials Group, the ANZIC Research Centre, the Australasian Society for Infectious Diseases Clinical Trials Group, the Paediatric Study Group of the ANZIC Society, and the ANZIC Society Centre for Outcome and Resource Evaluation. We thank Ville Pettilä for the provision of data from the ANZIC Influenza Investigators registry and assistance with some analysis, and the research coordinators and research midwives in all sites, who collected data. The study was coordinated by the Australian and New Zealand Intensive Care Research Centre, Monash University, Melbourne and the Australasian Maternity Outcomes Surveillance System, Perinatal and Reproductive Epidemiology Research Unit, University of New South Wales, Sydney, Australia.
Contributors: All members of the writing committee (see web extra on bmj.com for details) contributed equally to the collection and analysis of the data and drafting the manuscript, and take responsibility for the content of this manuscript.
Funding: The ANZIC Influenza Investigators registry is supported by the Department of Health and Ageing, Commonwealth Government of Australia; New South Wales Health, Government of New South Wales; Department of Health, Government of Victoria; the Australian and New Zealand Intensive Care Research Centre; the Australian and New Zealand Intensive Care Society; and an unrestricted grant from CSL, Melbourne, Victoria. The Australasian Maternity Outcomes Surveillance System is supported by National Health and Medical Research Council (Australia) project grant, No 510298. None of the funders had any role in the study design and the collection, analysis, and interpretation of data, or in the writing of the article and the decision to submit it for publication. The researchers confirm their independence from funders and sponsors. All researchers had access to all the data.
Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare that (1) no authors have support from any company for the submitted work; (2) no authors have any relationships with any companies that might have an interest in the submitted work in the previous 3 years; (3) their spouses, partners, or children have no financial relationships that may be relevant to the submitted work; and (4) no authors have non-financial interests that may be relevant to the submitted work.
Ethical approval: This study was approved by the institutional ethics committee of each centre and the requirement for individual subject informed consent was waived at all sites.
Data sharing: No additional data available.
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