Maternal Subclinical Hypothyroidism in the first trimester is not Associated with Gestational Diabetes Mellitus

Abstract Background: To explore the association between subclinical hypothyroidism (SCH) during the first trimester and gestational diabetes mellitus (GDM) that was happened later on in our cohort. Methods: A total of 6530 pregnant women who first visited before 13 +6 gestational weeks and accepted routinely prenatal services in the third affiliated hospital of Sun Yat-Sen University from January 2015 to September 2018 were finally met the inclusion criteria and recruited. Thyroid functions (TSH, free T4 (FT4) and TPOAb) were performed at the first visit and a 2h 75-g oral glucose tolerance test was performed between 24-28 weeks. Chi-square test and multivariate logistic regression were used to evaluate the association between SCH and GDM. Results: Though SCH group was divided into subgroups according TPOAb status and TSH levels, the incidence of GDM was no change when compared with the normal group (all P > 0.05). No matter adjusting or not for maternal age, maternal pregestational body max index, parity and educational level, the results showed elevated TSH was not associated GDM (all P > 0.05). TPOAb status also had no effect on the incidence of GDM either before or after adjustment ( P > 0.05). Conclusion: Maternal SCH in the first trimester was not associated with GDM, regardless of the TPOAb status or the TSH levels.