The complex interplay of duration of residence and region of birth on perinatal outcomes among migrant women in Australia — The Association Specialists
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The complex interplay of duration of residence and region of birth on perinatal outcomes among migrant women in Australia (23570)

Natalie Holowko 1 2 , Sol P Juárez 3 , Kirsten R Palmer 2 , Marian Knight 4 , Fatima El-Assaad 5 6 , Miranda Davies-Tuck 1 2
  1. Hudson Institute of Medical Research, Clayton, VIC, Australia
  2. Obstetrics and Gynaecology, Monash University, Clayton, Vic, Australia
  3. Public Health Sciences, Stockholm University, Stockholm, Sweden
  4. National Perinatal Epidemiology Unity, Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom
  5. Microbiome Research Centre, St George & Sutherland Clinical Campuses, School of Clinical Medicine, UNSW Medicine & Health, UNSW, Sydney, New South Wales, Australia
  6. The Still Nest, Sydney, New South Wales, Australia

 

Background

In high-income countries, initial health advantages among newly-arrived migrants often diminish with longer residence, with variation across outcomes and regions of birth. Despite migrant heterogeneity, research often emphasises origin over receiving-context factors. We investigated maternal risk factors and pregnancy outcomes by duration of residence in Australia, stratified by region of birth.
Methods 

This cohort study included singleton births in Victoria, Australia, 2017-2019 (N=217,136), 40% to women born outside Australia. Birth countries were grouped using UN-regions and residence duration categorised (<2, 2–5, >5–10, >10 years, Missing (~15%)). Outcomes included preconception health (smoking, BMI, pre-existing conditions), structural factors (antenatal care, early ultrasound, social disadvantage), and pregnancy outcomes (gestational diabetes, hypertensive disorders, gestation at birth, stillbirth). Associations were modelled using logistic/multinomial logistic regression, adjusted for maternal age and birth year, stratified by region of birth.

Results

Most migrant women were born in South-East/East Asia and South Asia (median residence 10 years). Compared to Australia-born women, migrants had lower odds of smoking (OR 0.16- 0.47), hypertension (OR 0.49- 0.78), BMI ≥25, and preeclampsia (OR 0.72-0.82) - although advantages were less pronounced with longer residence and varied by region. Some groups (Africa-, Oceania-, and South Asia-born) had higher odds of gestational diabetes (Africa: 2-5years OR 1.41 (1.19,1.67) to >10years OR 1.70 (1.53,1.88); Oceania: <2years OR 2.59 (1.60, 4.20) to >10years OR 2.86 (2.33,3.51); South Asia: <2years OR 2.70 (2.46, 2.97) to >10 years OR 3.56 (3.32, 3.83), stillbirth (Africa: <2years OR 3.36 (1.38, 8.15), >10 years OR 2.52 (1.68, 3.78); Oceania: >10years OR 2.72 (1.12, 6.59); South Asia: <2years OR 1.85 (1.15, 2.98), >5-10years OR 1.49 (1.08, 2.06), with some risks persisting regardless of duration.

Conclusion

Migrant health reflects region of origin and receiving-context conditions. Improving outcomes requires addressing structural barriers and upstream determinants disproportionately affecting specific migrant groups.