Background: Culturally and linguistically diverse (CALD) populations account for an increasing proportion of births in Australia. We examined associations between CALD status and adverse perinatal outcomes, and whether these varied by area-level socioeconomic position and remoteness in Western Australia.

Methods: Population-based retrospective cohort study included linked administrative perinatal data for singleton, non-Indigenous births in Western Australia (1980–2023). CALD status was defined by maternal country of birth or use of an interpreter during antenatal care. Outcomes were stillbirth and clinical categories of gestational age, birthweight, and birthweight-for-gestational-age. Adjusted logistic (stillbirth) and multinomial logistic (multi-category outcomes) regressions and interaction terms for area-level socioeconomic position (low/middle/high) and remoteness (major cities vs regional/remote) were performed.

Results: Among 520,720 births included, 0.3% were stillbirths, 6.5% preterm, 0.5% post-term, 4.5% low birthweight, 10.0% macrosomia, 7.1% small-for-gestational age, and 11.0% large-for-gestational age. Compared with non-CALD, CALD status was associated with higher odds of stillbirth (OR=1.51, 95% CI 1.08, 2.09), lower odds of preterm (OR=0.94, 95% CI 0.87, 1.01) and post-term (OR=0.97, 95% CI 0.74, 1.27), higher odds of low birthweight (OR=1.31, 95% CI 1.20, 1.42) and small-for-gestational age (OR=1.85, 95% CI 1.74, 1.97), and lower odds of macrosomia (OR=0.58, 95% CI 0.54, 0.62) and large-for-gestational age (OR=0.57, 95% CI 0.53, 0.61). Interaction effects showed consistent associations across socioeconomic and remoteness groups, except interaction with remoteness for large-for-gestational age (interaction OR=1.36, 95% CI 1.06, 1.75 in regional/remote vs major cities).

Conclusions: CALD status was associated with higher odds of stillbirth, low birthweight and small-for-gestational age, and lower odds of macrosomia and large-for-gestational age, while estimates for preterm and post-term were essentially consistent. Associations did not vary by area-level socioeconomic or remoteness, except for interaction with remoteness for large-for-gestational age. Culturally responsive maternity care and targeted prevention strategies are needed, with attention to place-based factors for large-for-gestational age.