This study aimed to explore the association between hyperglycemia in pregnancy (type 2 diabetes (T2D) and gestational diabetes mellitus (GDM)) and child developmental risk in Europid and Aboriginal women.PANDORA is a longitudinal birth cohort recruited from a hyperglycemia in pregnancy register, and from normoglycemic women in antenatal clinics. The Wave 1 substudy included 308 children who completed developmental and behavioral screening between age 18 and 60 months. Developmental risk was assessed using the Ages and Stages Questionnaire (ASQ) or equivalent modified ASQ for use with Aboriginal children. Emotional and behavioral risk was assessed using the Strengths and Difficulties Questionnaire. Multivariable logistic regression was used to assess the association between developmental scores and explanatory variables, including maternal T2D in pregnancy or GDM.After adjustment for ethnicity, maternal and child variables, and socioeconomic measures, maternal hyperglycemia was associated with increased developmental "concern" (defined as score ≥1 SD below mean) in the fine motor (T2D odds ratio (OR) 5.30, 95% CI 1.77-15.80; GDM OR 3.96, 95% CI 1.55-10.11) and problem-solving (T2D OR 2.71, 95% CI 1.05-6.98; GDM OR 2.54, 95% CI 1.17-5.54) domains, as well as increased "risk" (score ≥2 SD below mean) in at least one domain (T2D OR 5.33, 95% CI 1.85-15.39; GDM OR 4.86, 95% CI 1.95-12.10). Higher maternal education was associated with reduced concern in the problem-solving domain (OR 0.27, 95% CI 0.11-0.69) after adjustment for maternal hyperglycemia.Maternal hyperglycemia is associated with increased developmental concern and may be a potential target for intervention so as to optimize developmental trajectories.