Acculturation of Pacific mothers in New Zealand over time: findings from the Pacific Islands Families study

BACKGROUND: The epidemiological investigation of acculturation has often been hampered by inconsistent definitions and measurement, and methodological short-comings. Adopting a bi-directional model, with good theoretical and psychometric properties, this study aimed to describe the temporal, ethnic and socio-demographic influences of acculturation for a group of Pacific mothers residing in New Zealand. METHODS: Pacific mothers of a cohort of Pacific infants born at a large tertiary hospital in South Auckland in 2000 were interviewed at 6-weeks, 4-years and 6-years postpartum. At each measurement wave a home interview lasting approximately 90 minutes was conducted with each mother. Adapting the General Ethnicity Questionnaire, two scales of acculturation were elicited: one measuring New Zealand cultural orientation (NZAccult) and one measuring Pacific Islands cultural orientation (PIAccult). Acculturation scores were standardised and analysed using random intercept polynomial and piecewise mixed-effects regression models, accounting for the longitudinal nature of the repeated measured data. Mothers who immigrated to New Zealand and those who lived their lives in New Zealand were investigated separately. RESULTS: Overall, 1276 Pacific mothers provided 3104 NZAccult and 3107 PIAccult responses over the three measurement waves. Important and significant differences were observed in both bi-directional acculturation measures between the two maternal groups studied. New Zealand cultural orientation increased, on average, linearly with years lived in New Zealand both for immigrant mothers (0.013 per year, 95% CI: 0.012, 0.014), after adjusting for maternal age, and for mothers who lived their lives in New Zealand (0.008 per year, 95% CI: 0.06, 0.010). Immigrant mothers maintained their Pacific cultural orientation for, on average, 12 years before it began to linearly decrease with each year lived in New Zealand thereafter (-0.009 per year, 95% CI: -0.010, -0.008), after adjusting for maternal age. Mothers who lived their lives in New Zealand had a Pacific orientation that was, on average, unchanged regardless of the number of years lived in New Zealand. Significant ethnic and socio-demographic variations were noted. CONCLUSIONS: Understanding the patterns and trajectories of acculturation over time, and its key determinants, is necessary for the development of appropriate targeted health policy and care in typically vulnerable and marginalised immigrant populations.