Maternal region of birth and stillbirth in Victoria, Australia 2000–2011: A retrospective cohort study of Victorian perinatal data

RESEARCH ARTICLE Maternal region of birth and stillbirth in Victoria, Australia 2000–2011: A retrospective cohort study of Victorian perinatal data Miranda L. Davies-Tuck1*, Mary-Ann Davey2, Euan M. Wallace1,2 1 The Ritchie Centre, Hudson Institute of Medical Research, Clayton, Melbourne, Victoria, Australia, 2 Department of Obstetrics and Gynaecology, School of Clinical Sciences, Monash University, Clayton, Melbourne, Victoria, Australia a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 OPEN ACCESS Citation: Davies-Tuck ML, Davey M-A, Wallace EM (2017) Maternal region of birth and stillbirth in Victoria, Australia 2000–2011: A retrospective cohort study of Victorian perinatal data. PLoS ONE 12(6): e0178727. https://doi.org/10.1371/journal. pone.0178727 Editor: Kelli K Ryckman, Univesity of Iowa, UNITED STATES Received: January 24, 2017 Accepted: May 17, 2017 Published: June 6, 2017 Copyright: © 2017 Davies-Tuck et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: The data used in this manuscript was obtained from a third party and as such we do not own it. The data was provided by the Clinical Councils Unit at the Victorian Department of Health and Human Services. It is a population-based surveillance system that collects and analyses comprehensive information on the health of mothers and babies, in order to contribute to improvements in their health in Victoria. The data can be requested by contacting: Clinical Councils Unit, Department of Health & Human Services Email: * Abstract Background There is growing evidence from high-income countries that maternal country of birth is a risk factor for stillbirth. We aimed to examine the association between maternal region of birth and stillbirth between 2000 and 2011 inclusive in Victoria, Australia. Methods Retrospective population based cohort study of all singleton births at 24 or more weeks gestational age from 2000–2011 in Victoria, Australia. Stillbirths due to termination of pregnancy, babies with congenital anomalies and Indigenous mothers were excluded. Main Outcome Measure: Stillbirth. Results Over the 12-year period there were 685,869 singleton births and 2299 stillbirths, giving an overall stillbirth rate of 3
4 per 1000 births. After adjustment for risk factors, compared to women born in Australia/New Zealand, women born in South Asia (aOR 1.27, 95% CI 1.01– 1.53, p = 0.01), were more likely to have a stillbirth whereas women born in South East and East Asia were (aOR 0.60, (95% CI 0.49–0.72, p<0.001) less likely to have a stillbirth. Additionally, the increasing rate of stillbirth as gestation length progressed began to rise earlier and more steeply in the South Asian compared to Australian/New Zealand born women. The following risk factors were also significantly associated with an increased odds of stillbirth in multivariate analyses: maternal age <20 and 35 years and more, nulliparity, low socio-economic status, previous stillbirth, no ultrasound reported in 1st trimester, pre-existing hypertension, antepartum haemorrhage and failure to detect growth restriction antenatally. PLOS ONE | https://doi.org/10.1371/journal.pone.0178727 June 6, 2017 1 / 14 Maternal region of birth and stillbirth Location: 50 Lonsdale Street, Melbourne, 3000 Victoria, Australia. Funding: MDT received support from the Stillbirth Foundation of Australia to undertake this project. MDT also receives support from the National Health and Medical Research Council of Australia Fellowship program. EW receives funding from the Victorian Governments’ Operational Infrastructure Support Program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing interests: MDT has a secondment 1 day per week to CCOPMM. MAD is a part time employee of Clinical Councils Unit which manages the VPDC data and EW is a CEO of Safer Care Victoria, Department of health. These conflicts do not alter adherence to the PLOS ONE policies. Conclusion Maternal region of birth is an independent risk factor for stillbirth. Improvements in the rate of stillbirth, particularly late pregnancy stillbirth, are likely to be gained in high-income settings where clinical care is informed by maternal region of birth. Introduction There is still much to do in reducing the many preventable stillbirths that continue to occur in both high and low income countries[1–3]. Central to any effort in reducing the rate of stillbirth is a firm understanding of the key causes. Globally, the risk factors for stillbirth with the highest population attributable risks are advanced maternal age, maternal infections, non-communicable diseases, obesity, and prolonged pregnancy[3]. That many of these are increasing in prevalence [4] may explain, at least in part, why the rate of stillbirth is not decreasing despite advances in maternity care. One risk factor for stillbirth in high-income countries (HIC), for which there is growing evidence is maternal country of birth. It is widely appreciated that stillbirths are relatively more common among women of certain ethnic groups. However, this apparently increased risk has been mostly discussed in the context of migration and social disadvantage rather than ethnicity per se [3, 5]. While both migration, particularly for humanitarian reasons[6], and social disadvantage are risk factors for stillbirth we believe that they may have obscured the influence of maternal region of birth itself. Maternal region of birth has been shown to be an independent risk factor for stillbirth in many high-income countries including the UK[7, 8], the Netherlands[9], Sweden[10], Singapore[11], and, Australia[12, 13]. Compared to locally born women, women of South Asian or African birth have a significantly higher rate of stillbirth while women of South East/East Asian birth have a significantly lower rate. The differences are not trivial. In an urban Australian population South Asian born women were nearly two and a half times more likely to have a late pregnancy stillbirth than their Australian born counterparts accessing the same public maternity services[13]. Similarly, in the UK African, Indian and, Pakistani women were more than twice as likely to have a stillbirth than white women[7]. For two consecutive years the UK Perinatal MBRRACE reports have shown that the rate of stillbirth is significantly higher among black and Asian women than among others [14, 15]. However, only the American Congress of Obstetricians and Gynecologists (ACOG) clinical guidelines recognise “black women” as being at increased risk of stillbirth. While clinical guidelines from other leading authorities, such as the Royal College of Obstetricians and Gynaecologists, the National Inst (...truncated)