Effect of thyroxine level on gestational diabetes mellitus and pregnancy outcome

Objective　To investigate the effect of thyroxine level on the onset of gestational diabetes mellitus (GDM), pregnancy outcome and the basic conditions of neonates. Methods　The related information of 1903 cases of pregnant women were prospectively collected from the Department of Obstetrics, Shanghai Changhai Hospital. Selecting group A (gravida with low thyroxinemia, n=36), group B (gravida with pure thyroid peroxidase antibody (TPOAb) positive, n=113) and group C (gravida with normal thyroid function, n=1539) according to the results of thyroid function test in newly constructed card. The incidence of GDM and the related index of thyroid function and glucose metabolism during the second trimester of pregnancy were compared among the three groups. Gravida with GDM in the three groups were group D (9 cases), group E (32 cases) and group F (367 cases), respectively. The differences of pregnancy outcome and the basic conditions of neonates among them were compared. Results　 No significant differences existed (P>0.05) in the incidence of GDM during different pregnant period in groups A, B and C (First trimester: 50.00% vs. 25.00% vs. 34.69%; Second trimester: 21.88% vs. 28.71% vs. 22.70%). In the second trimester, the level of glycosylated hemoglobin (HbA1c) was significantly higher in group A than in group C [4.80%(4.60%, 5.00%) vs. 4.70%(4.40%, 4.90%)], while the fasting glucose level was significantly higher in group B than those in group C [(4.69±0.59) mmol/L vs. (4.58±0.43) mmol/L, P 0.05). Conclusions　Different levels of thyroxine have no significant effect on the incidence of GDM, but throw some effects on the glucose metabolism in the second trimester. In addition, positive TPOAb may increase the incidence of premature delivery and fetal distress in pregnant women with GDM, and affect fetal growth and development to some extent. Thyroid function status should be evaluated in the early stages of pregnancy, and regular follow-up should be conducted for patients with TPOAb positivity and timely intervention if necessary. DOI: 10.11855/j.issn.0577-7402.2020.04.13