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Article History

Received: 13 February 2018

Accepted: 26 July 2018

First Online: 8 August 2018

Ethics approval and consent to participate

: Ethics approval for this study was granted by the Human Research Ethics Committee of the University of New South Wales (HREC 11024) and the Australian Institute of Health and Welfare Ethics Committee (EC 2011/1/5).The dataset supporting the conclusion was pre-collected in non-identifiable format. Therefore, informed consent was waived by the ethics committee.

: Not applicable.

: Alex Wang is a member of the editorial board (Associate Editor) of BMC Pregnancy and Childbirth.

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