Maternal Obesity and Differences in Child Urine Metabolome

<b>Background/objective:</b> Approximately one-third of pregnant individuals in the U.S. are affected by obesity, which can adversely impact the in utero environment and offspring. This study aimed to investigate the differences in urine metabolomics between children exposed and unexposed to maternal obesity. <b>Methods:</b> In a study nested within a larger pregnancy cohort of women-offspring pairs, we measured untargeted metabolomics using liquid chromatography-mass spectrometry in urine samples from 68 children at 4-8 years of age. We compared metabolite levels between offspring exposed to maternal obesity (body mass index [BMI] ≥ 30.0 kg/m²) vs. unexposed (maternal BMI 18.5-24.9 kg/m²) and matched them on covariates, using two-sample t-tests, with additional sensitivity analyses based on children's BMI. This study reports statistically significant results (<i>p</i> ≤ 0.05) and potentially noteworthy findings (fold change > 1 or 0.05 < <i>p</i> < 0.15), considering compounds' involvement in common pathways or similar biochemical families. <b>Results:</b> The mean (SD) maternal age at study enrollment was 28.0 (6.3) years, the mean child age was 6.6 (0.8) years, 56% of children were male, and 38% of children had a BMI in the overweight/obese range (BMI ≥ 85th percentile). Children exposed to maternal obesity had lower levels of 5-hydroxyindole sulfate and 7-hydroxyindole sulfate and higher levels of secondary bile acids. Phenylacetic acid derivatives were lower in offspring exposed to obesity and in offspring who had a current BMI in the overweight/obese range. Exposure to maternal obesity was associated with lower levels of androgenic steroid dehydroepiandrosterone sulfate (DHEA-S). <b>Conclusions:</b> In this preliminary study, children exposed to maternal obesity in utero had differences in microbiome-related metabolites in urine suggestive of altered microbial catabolism of tryptophan and acetylated peptides. Some of these differences were partially attributable to the offspring's current BMI status. This study highlights the potential of urine metabolomics to identify biomarkers and pathways impacted by in utero exposure to maternal obesity.