Insufficient iodine intake based on 24-h urinary iodine excretion leads to significant metabolic changes in pregnant women at early stages of pregnancy

The effects of iodine insufficiency during the first and second trimesters on both pregnant women themselves and their offspring exhibit insufficient consistent patterns. In this study, we aimed to address this issue by employing small molecule metabolomics. A total of 98 pregnant women in either the first or second trimester were recruited, with comprehensive data including basic information, 24-h urine samples and blood samples collected, and subsequent evaluation of birth outcomes for their offspring. The 24-h urinary iodine excretion (UIE) was detected and used as the dividing criterion to determine the iodine nutrition status of pregnant women. Serum metabolomics was performed by Ultra High Performance Liquid Chromatography Orbitrap Exploris Mass Spectrometry (UHPLC-OE-MS) platform. Differential metabolites as potential iodine deficiency biomarkers were selected by multivariate statistical analysis methods. Association analysis was used to further analyze the relationship between the potential biomarkers and neonatal birth outcomes. There was no significant difference in maternal thyroid function indicators and neonatal outcomes between the insufficient iodine intake group and the iodine adequate pregnant women. However, the metabolic profile of pregnant women with iodine insufficiency was significantly disturbed compared to these with iodine adequate. A total of 28 different metabolites were screened, which could be used as potential biomarkers of iodine deficiency. After adjusted age and pregnancy trimester, the expression of these biomarkers were also changed significantly. Furthermore, these markers were also related to fatty acid biosynthesis, tyrosine metabolism, tryptophan metabolism, arachidonic acid metabolism, and pentose and glucuronate interconversions. In addition, among these markers, 2-(4-Methyl-5-thiazolyl)ethyl octanoate was found to be associated with neonatal TSH, ACar(12:0), (9S,10E,12Z,15Z)-9-Hydroxy-10,12,15-octadecatrienoic acid showed a correlation with body length; whereas (9S,10E,12Z,15Z)-9-Hydroxy-10,12,15-octadecatrienoic acid was linked to body weight. In conclusion, iodine insufficiency during the first and second trimesters dose not result in overt adverse effects on pregnant women and their offspring. However, at the metabolic level, insufficient iodine intake may disrupt the metabolic profile of pregnant women and impact the development of their offspring.