The parallel epidemics of obesity and Type 2 diabetes (T2DM) are progressing rapidly in Australia. The high prevalence of obesity and sedentary lifestyle in the population, compounded by later child bearing, has led to an increase in the prevalence of T2DM pre-dating pregnancy. In some centers, pregnant women with T2DM now outnumber those with type 1 diabetes (T1DM). Although there is controversy as to whether T2DM is associated with worse outcomes than T1DM in pregnancy, modern reports clearly acknowledge the seriousness of this condition. There is a clear association between obesity and adverse pregnancy outcomes (cesarean section, gestational diabetes, hypertensive disorders, birth defects and prematurity). Aside from obesity and the metabolic syndrome, additional factors may contribute to these adverse outcomes: A lack of preconception planning, a failure to achieve tight glycaemic control early in pregnancy and socio-economic disadvantage. It's likely that obesity and diabetes have compounding effects on pregnancy outcomes. In this review, we evaluate both the underlying pathogenesis of T2DM and obesity in the pregnancy context and the adverse clinical maternal and perinatal outcomes described in pregnancies complicated by maternal T2DM and obesity. We highlight the need for a comprehensive strategy to improve clinical outcomes in these pregnancies.