Thyroid antibodies and gestational diabetes mellitus: a meta-analysis

Objective: To determine whether thyroid antibodies are associated with an increased risk of gestational diabetes mellitus (GDM) in pregnant women.

Design: Meta-analysis.

Setting: Not applicable.

Patient(s): Twenty cohort and case-control studies involving pregnant women with positive thyroid antibodies were the exposure of interest, and GDM was the outcome.

Intervention(s): None.

Main outcome measure(s): A fixed-effects model was used to evaluate the relationship between thyroid antibodies and the risk of GDM. Subgroup analyses were performed among different types of study design, different thyroid antibodies, and patients with specific thyroid dysfunction.

Result(s): The search strategy identified 167 potentially relevant publications, of which 20 were included in the meta-analysis. A significant association between thyroid antibodies and GDM was observed. A meta-analysis of the 11 cohort studies with pregnant women with positive thyroid antibodies in their first trimester suggested no obvious risk of GDM compared with the reference group. In subgroup meta-analyses, no significant association between thyroid antibodies and GDM was found in euthyroid pregnant women, whereas a significant positive association was identified in women with a thyroid dysfunction.

Conclusion(s): Based on the currently available evidence, there is a significant but not strong association between thyroid antibodies and the risk of GDM, and thyroid antibodies in the first trimester lack predictive value for the risk of GDM. In addition, thyroid antibodies may not increase the risk of GDM in euthyroid pregnant women.