Evidence map›Paper›PMID 42635944›Full record

ArticleThe Medical journal of Australia2026

Temporal Trends in Preterm Birth Associated With Hypertensive Disorders of Pregnancy in Victoria, Australia: A Population-Based Interrupted Time-Series Study.

Melvin Marzan, Heng Jiang, Daniel Lorber Rolnik, Joanne M Said, Lisa Hui

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Article in The Medical journal of Australia, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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1 · What the graph read from it

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3 · Its place in the literature

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4 · The record

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5 · Who and what money

Authors and funding

5 authors.

Melvin MarzanDepartment of Obstetrics, Gynecology and Newborn Health, University of Melbourne, Heidelberg, Victoria, Australia.ORCID https://orcid.org/0000-0003-2696-7335
Heng JiangSchool of Psychology and Public Health, La Trobe University, Melbourne, Victoria, Australia.
Daniel Lorber RolnikDepartment of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia.ORCID https://orcid.org/0000-0002-2263-3592
Joanne M SaidDepartment of Obstetrics, Gynecology and Newborn Health, University of Melbourne, Heidelberg, Victoria, Australia.
Lisa HuiDepartment of Obstetrics, Gynecology and Newborn Health, University of Melbourne, Heidelberg, Victoria, Australia.ORCID https://orcid.org/0000-0002-9720-3562

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

objectivesHypertensive disorders of pregnancy (HDP) are a leading reason for medically indicated preterm birth (PTB), yet their contribution to population-level PTB trends is poorly understood. We examined temporal trends in PTB overall and HDP-associated PTB in Victoria over an 11-year period spanning the COVID-19 pandemic, and distinguished changes in HDP prevalence from changes in preterm delivery among affected pregnancies. STUDY TYPE: Population-based interrupted time-series study using seasonal autoregressive integrated moving average (SARIMA) models, with July 2018 (launch of a national preterm birth prevention program) pre-specified as a temporal reference point.

settingAll hospitals in Victoria, Australia.

participants779,325 singleton births at ≥ 20 weeks' gestation between 1 January 2012 and 31 March 2022.

main outcome measuresMonthly rates (per 1000 singleton births) of overall PTB, HDP and HDP-associated PTB. Decomposition analyses separated changes in HDP prevalence from changes in preterm delivery among affected pregnancies.

resultsOverall PTB was lower after July 2018 (5.8%-5.6%), while HDP prevalence increased (6.4%-7.0%). HDP-associated PTB increased before mid-2018 (+0.75 per 1000 births per month; 95% confidence interval [CI], 0.50-1.00) but declined thereafter (-1.12 per 1000 births per month; 95% CI, -1.88 to -0.36). This reversal was driven predominantly by reduced iatrogenic PTB with HDP; spontaneous PTB with HDP showed no significant change. Despite rising HDP prevalence, decomposition analyses estimated 89 fewer HDP-associated PTB cases than expected under pre-2018 patterns, reflecting a decline in the proportion of HDP pregnancies delivered preterm. PTB without HDP showed no significant temporal change.

conclusionPTB among HDP-complicated pregnancies declined despite increasing HDP prevalence, consistent with a shift towards later gestational age at delivery rather than reduced disease incidence. These findings may reflect improvements in care and demonstrate that reductions in iatrogenic PTB are achievable even as major risk factors become more prevalent.

Indexed as

Hypertension, Pregnancy-InducedPremature BirthAdultFemaleHumansInfant, NewbornInterrupted Time Series AnalysisPregnancyPrevalenceVictoriahigh‐risk pregnancyhypertensionperinatalpreterm birthpreterm labourwomen's health

Identifiers

PMID42635944
PMCPMC13502304

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.