The influence of acculturation on the risk of stillbirth in migrant women residing in Western Australia

OBJECTIVE: To investigate the influence of acculturation, demonstrated by age on arrival, length of residence, interpreter use and having an Australian-born partner, on disparities observed in the risk of stillbirth between migrant and Australian-born populations in Western Australia (WA). METHODS: A retrospective cohort study using linked administrative health data for all non-Indigenous births in WA from 2005–2013 was performed. Logistic regression analysis was used to estimate odds ratios (OR) and 95% confidence intervals (CI). Adjusted odds ratios (aOR) for stillbirth in migrants from six ethnicities of white, Asian, Indian, African, Māori, and ‘other’, with different levels of acculturation, were compared with Australian-born women using multivariable logistic regression analysis and marital status, maternal age group, socioeconomic status, parity, plurality, previous stillbirth, any medical conditions, any pregnancy complications, sex of baby, and smoking during pregnancy as the covariates. RESULTS: From all births studied, 172,571 (66%) were to Australian-born women and 88,395 (34%) to migrant women. Women from African, Indian and Asian backgrounds who gave birth in the first two years after arrival in Australia experienced the highest risk of stillbirth (aOR 3.32; 95% CI 1.70–6.47, aOR 2.71; 95% CI 1.58–4.65, aOR 1.93; 95% CI 1.21–3.05 respectively) compared with Australian-born women. This association attenuated with an increase in the length of residence in Asian and Indian women, but the risk of stillbirth remained elevated in African women after five years of residence (aOR 1.96 [1.10–3.49]). Interpreter use and an Australian-born partner were associated with 56% and 20% lower odds of stillbirth in migrants (p<0.05), respectively. CONCLUSIONS: Acculturation is a multidimensional process and may lower the risk of stillbirth through better communication and service utilisation and elevate such risk through increase in prevalence of smoking in pregnancy; the final outcome depends on how these factors are in play in a population. It is noteworthy that in women of African background risk of stillbirth remained elevated for longer periods after immigrating to Australia extending beyond five years. For migrants from Asian and Indian backgrounds, access to services, in the first two years of residence, may be more relevant. Enhanced understanding of barriers to accessing health services and factors influencing and influenced by acculturation may help developing interventions to reduce the burden of stillbirth in identified at-risk groups.