Association Between Maternal Thyroid Hormone Concentration with Normal Thyroid Function During Pregnancy and Preschoolers’ Glycolipid Metabolism: A Birth Cohort Study

Background: Thyroid hormones (THs) are essential endocrine hormones that play key roles in individual's growth and development. There is limited knowledge about the association between maternal TH concentrations variations with normal thyroid function during pregnancy and offspring's glycolipid metabolism. Methods: A total of 1130 mother-child pairs from the Ma'anshan birth cohort were included in this prospective study. Maternal TH levels and thyroid peroxidase antibodies were measured in the 1st, 2nd, and 3rd trimesters of pregnancy during the childhood follow-up period. Fasting venous blood was collected from children at 4-6 years of age and glycolipid metabolic indicators were assayed. Analyses were performed using Binary logistic regression models, linear regression models, and Generalized linear regression model. Results: Maternal TH trajectories were fitted via latent category growth models. During the 1st trimester of pregnancy, maternal T3 and free thyroxine (fT4) levels were positively associated with children's blood glucose levels (β = 0.007 [CI 0.028-0.181]; β = 0.022 [CI 0.004-0.040]), whereas high levels of fT4 may be associated with decreased risk of children's hypercholesterolemia (OR = 0.870 [CI 0.768-0.986]). Maternal T4 concentrations during the 3rd trimester of pregnancy were negatively associated with children's cholesterol levels (β = -0.002 [CI -0.003-0.00]). High maternal TH levels were associated with high fasting glucose level and low low-density lipoprotein concentrations in children. Conclusions: Maternal TH dynamic variations may be associated with glycolipid metabolism in preschoolers, even when women do not have clinically diagnosed thyroid disorders. The exact associations between maternal THs in specific trimesters of pregnancy under normal thyroid function conditions and glycolipid metabolism in offspring require further investigation.