Limitations of the study
INSULIN RESISTANCE
Maternal blood was not collected in the fasting state, which increases biological variability for some metabolites. Data on diet (MS is a powerful tool, but the metabolites identified provide only a snapshot of metabolism at key timepoints in the life of mother and child. Cord blood was taken immediately after delivery, a highly dynamic time in metabolism which is difficult to study in humans with clarity. While we adjusted for key perinatal exposures, such as gestational age at delivery, maternal glycaemia and Caesarean section, we cannot exclude the possibility of other influences, which we could not resolve statistically. Despite these limitations, the cord blood results provide intriguing data about early life, and are useful for generating new hypotheses.A further limitation is that insulin, the master regulator of carbohydrate, lipid and protein metabolism, was not directly measured in this study. Inadequate insulin supply, through inadequate dosing for maternal diet or insulin resistance, results in insufficient carbohydrate availability for cellular metabolism, provoking mobilisation of lipid and protein stores to meet fuel requirements.