Geospatial Determinants of Maternal Overweight, Gestational Diabetes and Large for Gestational Age Birthweight in Melbourne During and After COVID-19 Lockdowns.

Abstract

Background: Research has linked postcode-level sociodemographic, food and built environment factors to maternal and perinatal outcomes like overweight (BMI > 25 kg/m²), gestational diabetes mellitus (GDM) and large for gestational age (LGA) birthweight. However, little is known about how these factors were influenced by the COVID-19 pandemic. We examine how postcode-level indicators and lockdown conditions are associated with the prevalence of maternal overweight, GDM and LGA.

Materials and methods: We analysed birth records from 12 public maternity hospitals in Melbourne, integrating postcode-level environmental indicators. Spatial regression models assessed associations between these indicators and maternal health outcomes, distinguishing between (a) the COVID-19 lockdown and (b) post-lockdown periods.

Results: We included 31 083 singleton birth records from 2020 to 2023 across 235 postcodes in Greater Melbourne. The prevalence of maternal overweight, GDM and LGA were 496, 178 and 103 per 1000 births, respectively. Maternal overweight was less prevalent in postcodes with higher median ages and socioeconomic scores, with disparities intensifying during lockdowns. GDM was more common in areas with younger, overseas-born populations, while LGA correlated with higher median age and fewer overseas-born residents. Notably, maternal overweight mediated the effect of socioeconomic status on GDM and LGA.

Conclusions: The prevalence of maternal overweight, GDM and LGA varies significantly across Melbourne, shaped by postcode-level factors. The pandemic lockdown amplified existing health disparities. The food and built-environment factors independently influence maternal and perinatal outcomes.