Perinatal mortality among term births: Informing decisions about singleton early term births in Western Australia.

BACKGROUND: To minimise the risk of perinatal mortality, clinicians and expectant mothers must understand the risks and benefits associated with continuing the pregnancy. OBJECTIVES: Report the gestation-specific risk of perinatal mortality at term. METHODS: Population-based cohort study using linked health data to identify all singleton births at gestations 37-41 weeks, in Western Australia (WA) from 2009 to 2019. Lifetable analysis was used to combine the risk of each type of perinatal mortality and calculate the cumulative risk of perinatal mortality, termed the perinatal risk index (PRI). Rates of antepartum and intrapartum stillbirth and neonatal death, as well as the PRI, were examined for each gestational week at term by non-Aboriginal and Aboriginal ethnicity. For non-Aboriginal women, rates were also examined by time-period (pre- vs. post-WA Preterm Birth Prevention Initiative (the Initiative) rollout), primiparity, and obstetric risk. RESULTS: There were 332,084 singleton term births, including 60 perinatal deaths to Aboriginal mothers (3.2 deaths per 1000 births to Aboriginal mothers) and 399 perinatal deaths to non-Aboriginal mothers (1.3 deaths per 1000 births to non-Aboriginal mothers). For non-Aboriginal women, the PRI was at its lowest (PRI 0.80, 95% CI 0.61, 1.00) at 39 weeks gestation. For Aboriginal women, it was at its lowest at 38 weeks (PRI 2.43, 95% CI 0.48, 4.39) with similar risk at 39 weeks (PRI 2.68, 95% CI 1.22, 4.14). The PRI increased steadily after 39 weeks gestation. The risk of perinatal mortality was higher among Aboriginal women. The gestation-specific perinatal mortality rates were similar by the time-period, primiparity and obstetric risk. CONCLUSIONS: The gestational ages at term associated with the lowest risk of perinatal mortality reinforce that the recommendation not to deliver before 39 weeks without medical indication is applicable to both Aboriginal and non-Aboriginal women giving birth in WA. There was no increase in the perinatal mortality rate associated with the introduction of the Initiative.

A retrospective, longitudinal cohort study of trends and risk factors for preterm birth in the Northern Territory, Australia.

BACKGROUND: Preterm birth (PTB) is the single most important cause of perinatal mortality and morbidity in high income countries. In Australia, 8.6% of babies are born preterm but substantial variability exists between States and Territories. Previous reports suggest PTB rates are highest in the Northern Territory (NT), but comprehensive analysis of trends and risk factors are lacking in this region. The objective of this study was to characterise temporal trends in PTB among First Nations and non-First Nations mothers in the Top End of the NT over a 10-year period and to identify perinatal factors associated with the risk of PTB. METHODS: This was a retrospective population-based cohort study of all births in the Top End of the NT over the 10-year period from January 1st, 2008, to December 31st, 2017. We described maternal characteristics, obstetric complications, birth characteristics and annual trends in PTB. The association between the characteristics and the risk of PTB was determined using univariate and multivariate generalised linear models producing crude risk ratios (cRR) and adjusted risk ratios (aRR). Data were analysed overall, in First Nations and non-First Nations women. RESULTS: During the decade ending in 2017, annual rates of PTB in the Top End of the NT remained consistently close to 10% of all live births. However, First Nations women experienced more than twice the risk of PTB (16%) compared to other women (7%). Leading risk factors for PTB among First Nations women as compared to other women included premature rupture of membranes (RR 12.33; 95% CI 11.78, 12.90), multiple pregnancy (RR 7.24; 95% CI 6.68, 7.83), antepartum haemorrhage (RR 4.36; 95% CI 3.93, 4.84) and pre-existing diabetes (RR 4.18; 95% CI 3.67, 4.76). CONCLUSIONS: First Nations women experience some of the highest PTB rates globally. Addressing specific pregnancy complications provides avenues for intervention, but the story is complex and deeper exploration is warranted. A holistic approach that also acknowledges the influence of socio-demographic influences, such as remote dwelling and disadvantage on disease burden, will be required to improve perinatal outcomes.

Ascertainment of Aboriginal and Torres Strait Islander status for assessment of perinatal health outcomes: Reported versus derived maternal ethnicity in Western Australian pregnancy data.

BACKGROUND: Under-identification of Aboriginal and Torres Strait Islander (hereafter referred to as Aboriginal) people can result in inaccurate estimation of health outcomes. Data linkage has improved identification of Aboriginal people in administrative datasets. AIM: To compare three methods of ascertainment of Aboriginal status using only pregnancy data from the Western Australian Midwives Notification System (MNS), to the linked Indigenous Status Flag (ISF) derived by the Department of Health. MATERIALS AND METHODS: This retrospective population-based cohort study utilised logistic regression to determine which demographic characteristics were associated with under-identification, and the effect of ascertainment method on perinatal adverse outcomes. RESULTS: All methods identified a core group of 19 017 (83.0%) Aboriginal women and the ISF identified 2298 (10.0%) women who were not identified using any other method. Under-ascertainment was lowest when a woman's Aboriginal status was determined by ever being recorded as Aboriginal in the MNS data, and highest when taken as it had been recorded for the birth in question. Maternal age <20 years, smoking during pregnancy, pre-existing diabetes, a history of singleton preterm birth and being in the lowest 20% of Socio-Economic Indexes for Areas score were all associated with a higher chance of being identified by the methods using only the MNS. These methods were less likely to identify nulliparous women, and those with maternal age ≥35 years. The method of ascertainment of Aboriginality did not make a significant difference to the adjusted predicted marginal probabilities of adverse perinatal outcomes. CONCLUSION: Unlinked pregnancy data can be used for epidemiological research in Aboriginal obstetric populations.

The Western Australian preterm birth prevention initiative: a whole of state singleton pregnancy cohort study showing the need to embrace alternative models of care for Aboriginal women.

BACKGROUND: Preterm birth (PTB) is the greatest cause of mortality and morbidity in children up to five years of age globally. The Western Australian (WA) PTB Prevention Initiative, the world's first whole-of-population whole-of-state program aimed at PTB prevention, was implemented across WA in 2014. METHODS: We conducted a prospective population-based cohort study using pregnancy data for singleton births in WA from 2009 to 2019. Logistic regression using the last full year before the Initiative (2013) as the reference, and run charts were used to examine changes in PTB rates compared to pre-Initiative levels, by gestational age group, hospital type, low and high risk of PTB in mid-pregnancy, and onset of labour (spontaneous/medically initiated). Analyses were stratified by Aboriginal and non-Aboriginal maternal ethnicity. RESULTS: Amongst non-Aboriginal women, there was initially a reduction in the PTB rate across the state, and in recent years it returned to pre-Initiative levels. Amongst Aboriginal women there was a small, non- significant reduction in the state-wide PTB rate in the first three years of the Initiative, followed by a rise in recent years. For non-Aboriginal women, the reduction in the rate of PTB at the tertiary centre was sustained and improved further for women of all risk levels and onsets of labour. This reduction was not observed for Aboriginal women giving birth at the tertiary centre, amongst whom there was an increase in the PTB rate overall and in all subgroups, with the exception of medically initiated PTB. Amongst Aboriginal women the PTB rate has also increased across the state. At non-tertiary hospitals there was a large increase in PTB amongst both Aboriginal and non-Aboriginal women, largely driven by medically initiated late PTB. Maternal risk factors cannot account for this increase. CONCLUSIONS: The reduction in PTB rates amongst non-Aboriginal women at the state's tertiary hospital demonstrates that with the right strategies, PTB can be reduced. A sustained collaborative model is required to realise this success in non-tertiary hospitals. The series of interventions was of limited use in Aboriginal women, and future efforts will need to be directed at strategies more likely to be successful, such as midwifery continuity of care models, with Aboriginal representation in the healthcare workforce.

Short cervix and preterm birth in the top end.

BACKGROUND: Reducing rates of preterm birth (PTB) remains a significant challenge. The Northern Territory (NT) records some of the highest rates of PTB in the country, especially in First Nations women. In 2014, a Western Australian (WA) preterm birth prevention initiative involved the implementation of seven key initiatives. One of these was routine mid-trimester cervical length measurement. The initiative successfully reduced PTB rates following its first year of implementation. This was the first successful reduction in PTB, including the earlier gestational ages, across a population. AIMS: To assess the uptake of routine cervical length measurement in the Top End of the NT after the success of the WA PTB prevention initiative and assess if treatment of a short cervix improved PTB rates. METHODS: A retrospective cohort study of all women who received antenatal care and delivered their baby at the NT's only tertiary hospital was performed. Mid-trimester ultrasound scan data were collected from two separate time windows, before and after the implementation of the WA intervention. Treatments and gestational age at birth were recorded. RESULTS: Adoption of routine screening of cervical length measurement at mid-trimester ultrasound in the NT was successful, increasing from 4 to 88%. Detection rates of short cervix doubled. However, there was no difference to PTB rates despite targeted management. CONCLUSION: PTB remains a significant challenge in the NT, especially for First Nations women who are found to have a short cervix more commonly than non-Indigenous women in the Top End.

The health and educational costs of preterm birth to 18 years of age in Australia.

BACKGROUND: Preterm birth is the greatest cause of death up to five years of age and an important contributor to lifelong disability. There is increasing evidence that a meaningful proportion of early births may be prevented, but widespread introduction of effective preventive strategies will require financial support. AIMS: This study estimated the economic cost to the Australian government of preterm birth, up to 18 years of age. MATERIALS AND METHODS: A decision-analytic model was developed to estimate the costs of preterm birth in Australia for a hypothetical cohort of 314 814 children, the number of live births in 2016. Costs to Australia's eight jurisdictions included medical expenditures and additional costs to educational services. RESULTS: The total cost of preterm birth to the Australian government associated with the annual cohort was estimated at $1.413 billion (95% CI 1047-1781). Two-thirds of the costs were borne by healthcare services during the newborn period and one-quarter of the costs by educational services providing special assistance. For each child, the costs were highest for those born at the earliest survivable gestational age, but the larger numbers of children born at later gestational ages contributed heavily to the overall economic burden. CONCLUSION: Preterm birth leaves many people with lifelong disabilities and generates a significant economic burden to society. The costs extend beyond those to the healthcare system and include additional educational needs. Assessments of economic costs should inform economic evaluations of interventions aimed at the prevention or treatment of preterm birth.

Association between maternal mental health-related hospitalisation in the 5 years prior to or during pregnancy and adverse birth outcomes: a population-based retrospective cohort data linkage study in the Northern Territory of Australia.

Background: Mental health conditions prior to or during pregnancy that are not addressed can have adverse consequences for pregnancy and birth outcomes. This study aimed to determine the extent to which women's mental health-related hospitalisation (MHrH) prior to or during pregnancy was associated with a risk of adverse birth outcomes. Methods: We linked the perinatal data register for all births in the Northern Territory, Australia, from the year 1999 to 2017, to hospital admissions records to create a cohort of births to women aged 15-44 years with and without MHrH prior to or during pregnancy. We used Modified Poisson Regression and Latent Class Analysis to assess the association between maternal MHrH and adverse birth outcomes (i.e., stillbirth, preterm birth, low birth weight, and short birth length). We explored a mediation effect of covariates on theoretical causal paths. We calculated the adjusted Population Attributable Fraction (PAF) and Preventive Fractions for the Population (PFP) for valid associations. Findings: From 72,518 births, 70,425 births (36.4% for Aboriginal women) were included in the analysis. The Latent Class Analys identified two classes: high (membership probability of 10.5%) and low adverse birth outcomes. Births to Aboriginal women with MHrH were around two times more likely to be in the class of high adverse birth outcomes. MHrH prior to or during pregnancy increased the risk of all adverse birth outcomes in both populations with risk ranging from 1.19 (95% CI: 1.05, 1.35) to 7.89 (1.17, 53.37). Eight or more antenatal care visits and intrauterine growth restriction mostly played a significant mediation role between maternal MHrH and adverse birth outcomes with mediation effects ranging from 1.04 (1.01, 1.08) to 1.39 (1.14, 1.69). MHrH had a low to high population impact with a PAF ranging from 16.1% (5.1%, 25.7%) to 87.3% (14.3%, 98.1%). Eight or above antenatal care visits avert extra adverse birth outcomes that range from 723 (332-765) stillbirths to 3003 (1972-4434) preterm births. Interpretation: Maternal MHrH is a modifiable risk factor that explained a low to moderate risk of adverse birth outcomes in the Northern Territory. The knowledge highlights the need for the development and implementation of preconception mental health care into routine health services. Funding: The Child and Youth Development Research Partnership (CYDRP) data repository is supported by a grant from the Northern Territory Government.

A better start to life: Risk factors for, and prevention of, preterm birth in Australian First Nations women - A narrative review.

The unacceptable discrepancies in health outcomes between First Nations and non-Indigenous Australians begin at birth. Preterm birth (birth before 37 completed weeks of gestation) is a major contributor to adverse short- and long-term health outcomes and mortality. Australian First Nations infants are more commonly born too early. No tangible reductions in preterm births have been made in First Nations communities. Factors contributing to high preterm birth rates in Australian First Nations infants are reviewed and interventions to reduce preterm birth in Australian First Nations women are discussed. More must be done to ensure Australian First Nations infants get a better start to life. This can only be achieved with ongoing and improved research in partnership with Australian First Nations peoples.