The association between antithyroid antibodies in euthyroid women with recurrent pregnancy Loss Before and During Pregnancy

Background: Antithyroid antibodies(ATAb),especially thyroid peroxidase antibodies (TPOAb), have been found to be related to recurrent pregnancy loss (RPL),but this relationship mainly focus on the patients before pregnancy. The aim of this study was to evaluate the association of ATAb with RPL before and during Pregnancy. Materials and Methods: The clinical data of women with RPL or with spontaneous pregnancy loss (SPL), who met inclusion criteria were registered from January 2017 to January 2024, were retrospectively analyzed. The presence of ATAb with times of SPL, the changes of ATAb before pregnancy and during in 19 to 28 weeks of gestation（19-28 WG） were noted. Results: In 19-28 WG, among the patients with 0, 1 and ≥2 times of SPL,and among TGAb positive patients with 0, 1 and ≥2 times of SPL, the TGAb concentrations were the highest in patients with ≥2 times of SPL ( P = 0.001 and 0.044), the TGAb concentrations in patients with 1 and ≥2 times of SPLwere significantly higher than that in patients with 0 time of SPL(P =0.0004 and 0.001; P =0.022 and 0.024). Before pregnancy, in patients with 1 and ≥2 times of SPL, the TGAb concentration were significantly lower(P =0.01 and 0.012), the TPOAb concentration were significantly higher(P =0.001 and 9.6E-7) than that in 19-28WG; in TGAb negative patients with 1 time of SPL,TGAb concentration were significantly lower(P =0.031) than that in 19-28WG;in ATAb , TGAb and TPOAb negative patients with ≥2 times of SPL,the concentration of TPOAb were significantly lower(P =0.002, 0.007 and 0.0004) than that in 19-28WG. Conclusions: In midtrimester of pregnancy,TGAb concentration increase,while TPOAb decrease, the association of TPOAb with SPL may become less obvious, but the association of TGAb with SPL may be much obvious, especially with ATAb, TGAb and TPOAb negative patients, TGAb may be a biomarker of pregnant women with history of RPL.