Being a First Nations baby is not independently associated with low birthweight in a large metropolitan health service.

Aim: To examine low birth weight (LBW) in First Nations babies born in a large metropolitan health service in Queensland, Australia.

Materials and methods: A retrospective population-based study using routinely collected data from administrative data sources. All singleton births in metropolitan health services, Queensland, Australia of ≥20 weeks gestation or at least 400 g birthweight and had information on First Nations status and born between 2019 and 2021 were included. The study measured birthweight and birthweight z-score, and also identified the predictors of LBW. Multivariate regression models were adjusted by demographic, socioeconomic and perinatal factors.

Results: First Nations babies had higher rates of LBW (11.4% vs 6.9%, P < 0.001), with higher rates of preterm birth (13.9% vs 8.8%, P < 0.001). In all babies, the most important factors contributing to LBW were: maternal smoking after 20 weeks of gestation; maternal pre-pregnancy underweight (body mass index <18.5 kg/m²); nulliparity; socioeconomic disadvantage; geographical remoteness; less frequent antenatal care; history of cannabis use; pre-existing cardiovascular disease; pre-eclampsia; antepartum haemorrhage; and birth outcomes including prematurity and female baby. After adjusting for all contributing factors, no difference in odds of LBW was observed between First Nations and non-First Nation babies.

Conclusions: First Nations status was not an independent factor influencing LBW in this cohort, after adjustment for identifiable factors. The disparity in LBW relates to modifiable risk factors, socioeconomic disadvantage, and prematurity. Upscaling culturally safe maternity care, focusing on modifiable risk factors is required to address LBW in Australian women.