Introduction Fetal macrosomia is associated with an increase in adverse obstetric outcome and also confers a future risk of childhood obesity. Metabolomics is a novel technology studying small molecule metabolite profiles in biological samples. The aim of this study was to determine if early pregnancy urinary metabolomic profile could predict macrosomia among mothers subjected to pregnancy dietary intervention.

Methods Women were recruited as part of an ongoing randomised control trial of maternal low glycaemic index (GI) diet in the prevention of macrosomia. Fasting first trimester urine samples from 27 women in the intervention arm prior to commencing a low GI diet were analysed using NMR spectroscopy.

Results Principal component analysis of the first trimester urine showed significant separation in spectra according to birth weight. PLS-DA analysis was employed and a significant model separating subjects according to birth weight was built (nine delivered infants with birth weight >4.5 kg and 18 delivered infants with birth weight <4.5 kg). 18 spectral bin regions were found to be significantly different between the two groups; further work is needed to validate this model in larger cohort.

Discussion This preliminary data showed a significant difference in the urinary metabolomic profile of women who subsequently delivered a macrosomic baby compared to those who did not. This novel technology has the potential to identify from early pregnancy women likely to respond to dietary intervention in the prevention of macrosomia. Worldwide childhood obesity is a growing health concern; these findings hold potential to allow for pregnancy interventions to reduce its incidence.