Background:

A high proportion of women start pregnancy overweight/obese. According to the developmental overnutrition hypothesis, this could cause offspring to be fatter throughout their lives, and therefore, this may perpetuate the obesity epidemic across generations.1, 2 Concerns about this hypothesis are influencing antenatal care. Two key changes to antentatal care which have occurred in relation to concerns about developmental overnutrition are:

1.Monitoring weight throughout pregnancy. This was previously done with the aim of identifying those at risk of SGA, but was stopped in the mid-1990s because of evidence of its poor predictive value.3 It is now being done with the intent of limiting gestational weight gain (GWG) in order to prevent women having infants who are LGA, since they may go on to be more adipose throughout their lives.4

2.The new International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria for defining gestational diabetes (GDM), which have been adopted by the WHO, aim to identify those at risk of LGA and greater offspring adiposity.5

However, whether the associations of maternal adiposity with offspring outcomes are causal is unknown, and if they are indeed causal, then the mechanisms are unclear.1, 2 Being able to accurately quantify maternal and fetal fat mass, glucose variability, diet, physical activity and a wide range of potential circulating nutrients in women during pregnancy could clarify the effects of maternal overweight/adiposity on her future health and that of her offspring. Having tools for obtaining these data that are acceptable, feasible, cost-effective and safe in pregnancy would support translation of research findings into clinical practice as appropriate.