Association between thyroid function and risk of gestational diabetes mellitus in assisted pregnancies: a retrospective cohort study

Abstract Aims To explore the association between thyroid function and gestational diabetes mellitus (GDM) risk in assisted pregnancies. Methods We screened 57,386 pregnant women treated from February 2013 to October 2017, and 2,211 patients were retrospectively enrolled, and their data were analyzed based on quintile groups constituted based on serum thyroid-stimulating hormone (TSH), free thyroxine (FT4), and thyroid peroxidase antibody (TPOAb) levels. Odds ratios (ORs) of GDM were analyzed by multivariate logistic regression, adjusted for maternal age and pre-pregnancy body mass index (BMI). Results The prevalence rate of GDM was 20.1%. Lower FT4 levels were associated with an increased risk of GDM (ORQ2=1.512, 95% confidence interval [CI] 1.073–2.132, p=0.018; ORQ1=1.620, 95% CI 1.161–2.261, p=0.005), but this association disappeared after adjustments. TPOAb+ titer was associated with an increased risk of GDM (aOR=1.472, 95% CI 1.068–2.028, p=0.018). Higher TSH (aORQ5=2.882, 95% CI 1.919–6.975, p=0.019) or lower FT4 (aORQ1=3.156, 95% CI 1.088–9.115, p=0.034) levels were associated with an increased risk of GDM in assisted pregnancies for TPOAb+ patients. Conclusion TPOAb+ is an independent risk factor for GDM in patients with assisted pregnancies. Higher TSH or lower FT4 levels, with TPOAb+ detection, are risk factors for GDM in assisted pregnancies.