The global obesity epidemic has been causally linked to changes in diet and lifestyle. Observational data and animal studies have now highlighted associations between in utero environmental exposures and increased susceptibility to obesity and related cardiometabolic disorders in later life. Maternal body mass index has been reported to show an independent association with offspring adiposity from an early age and to play an important role in the predisposition to obesity and metabolic disease in later life. Thus, the in utero environment has been the focus of recent targeted interventions to improve public health. In this review, we summarize recent progress in this field, including the use of animal models to investigate mechanistic links between maternal obesity and offspring metabolic risk. We then assess the level of evidence and challenges in establishing causal inferences from present birth cohorts.