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.

Randomised controlled trial of perinatal vitamin D supplementation to prevent early-onset acute respiratory infections among Australian First Nations children: the 'D-Kids' study protocol.

INTRODUCTION: Globally, acute respiratory infections (ARIs) are a leading cause of childhood morbidity and mortality. While ARI-related mortality is low in Australia, First Nations infants are hospitalised with ARIs up to nine times more often than their non-First Nations counterparts. The gap is widest in the Northern Territory (NT) where rates of both acute and chronic respiratory infection are among the highest reported in the world. Vitamin D deficiency is common among NT First Nations neonates and associated with an increased risk of ARI hospitalisation. We hypothesise that perinatal vitamin D supplementation will reduce the risk of ARI in the first year of life. METHODS AND ANALYSIS: 'D-Kids' is a parallel (1:1), double-blind (allocation concealed), randomised placebo-controlled trial conducted among NT First Nations mother-infant pairs. Pregnant women and their babies (n=314) receive either vitamin D or placebo. Women receive 14 000 IU/week or placebo from 28 to 34 weeks gestation until birth and babies receive 4200 IU/week or placebo from birth until age 4 months. The primary outcome is the incidence of ARI episodes receiving medical attention in the first year of life. Secondary outcomes include circulating vitamin D level and nasal pathogen prevalence. Tertiary outcomes include infant immune cell phenotypes and challenge responses. Blood, nasal swabs, breast milk and saliva are collected longitudinally across four study visits: enrolment, birth, infant age 4 and 12 months. The sample size provides 90% power to detect a 27.5% relative reduction in new ARI episodes between groups. ETHICS AND DISSEMINATION: This trial is approved by the NT Human Research Ethics Committee (2018-3160). Study outcomes will be disseminated to participant families, communities, local policy-makers, the broader research and clinical community via written and oral reports, education workshops, peer-reviewed journals, national and international conferences. TRIAL REGISTRATION NUMBER: ACTRN12618001174279.