Association of Maternal Thyroglobulin Antibody With Preterm Birth in Euthyroid Women

Context While the association between maternal thyroid peroxidase antibody (TPOAb) positivity and preterm birth (PTB) risk has been established, the association between thyroglobulin antibody (TgAb) and PTB remains unclear.Objective This study aimed to explore the association between TgAb and PTB risk in euthyroid women.Methods This single-center, prospective cohort study enrolled euthyroid women in the first trimester. Data on serum concentrations of thyrotropin (TSH), free thyroxine (FT4), TgAb, and TPOAb were collected. Participants were categorized into 2 groups (TgAb-negative and TgAb-positive). PTB was subtyped into spontaneous PTB (S-PTB) and medically induced PTB (MI-PTB); and into early PTB (E-PTB) and late PTB (L-PTB). Logistic regression models examined the associations between TgAb and PTB and its subtypes, with stratification by first-trimester TSH levels (0.1-2.5 mIU/L, 2.5-4.0 mIU/L).Results This study comprised 58 247 euthyroid pregnant women. Adjusting for confounders, TgAb positivity was associated with a 16% increased risk of PTB (adjusted odds ratio (aOR) 1.16, 95% CI, 1.03-1.29; P = .01) compared to the TgAb-negative group. Specifically, TgAb positivity showed a higher risk of S-PTB and L-PTB, aOR 1.22 (95% CI, 1.06-1.39) and aOR 1.17 (95% CI, 1.04-1.32), respectively. Consistent results were observed when analyzing TgAb concentration as a continuous variable. TSH stratification analysis revealed that these associations were statistically significant only among women with TSH levels between 0.1 and 2.5 mIU/L.Conclusion In euthyroid women, TgAb positivity was associated with a higher risk of PTB that mainly manifested as S-PTB and L-PTB. However, the clinical significance of these findings is limited.