Untreated thyroid autoantibody-negative SCH increases the risk of spontaneous abortions

Abstract

Background: Numerous studies have found that subclinical hypothyroidism (SCH) may increase the adverse pregnancy outcomes; however, the benefit of levothyroxine (LT4) treatment remains controversial.Therefore, the primary goal of this study was to investigate the correlation between thyroid autoantibodies negative-SCH with or without LT4 treatment and adverse pregnancy outcomes. Methods: 1344 women involved the study according the inclusion and exclusion criteria. Assays for thyroid stimulating hormone (TSH), free thyroxine (FT4), anti-thyroid peroxidase antibody (TPOAb), anti-thyroglobulin antibody (TGAb) and laboratory indicators were performed. The participants were divided into the euthyroid group (n = 1250) and the SCH group(n=94). The SCH group was further divided into LT4 group (n =40) and non-LT4 group(n=54). The laboratory indicators and pregnancy outcomes were evaluated during follow-ups. Results: There were no significant differences in lipid profile and homocysteine levels between ET and SCH group in the first and third trimester of pregnancy (P<0.05). After adjusting the confounding factors, the non-LT4 group was a risk factor for spontaneous abortion (OR: 3.141, 95% CI: 1.060-9.302). Survival analysis showed that the time of abortion was different between the ET group and SCH group (Log-rank P=0.042). The spontaneous abortion of SCH, especially non-LT4 group mainly occurred in the first trimester of pregnancy. Conclusions: Thyroid autoantibody negative-SCH seems to be associated with increased risk of spontaneous abortions during first trimester of pregnancy. LT4 therapy in this patient population might be beneficial to reduce adverse pregnancy outcomes.

Lipid Metabolism in Pregnancy Women with Hypothyroidism and Potential Influence on Pregnancy Outcome

“…SCH is also associated with alterations in lipid profiles, although the extent and impact of these changes are still under investigation (as shown in Figure 2 ). Observational studies have shown that SCH patients in early pregnancy have TC, TG, HDL-c, and LDL-c levels than normal pregnant women [ 18 ]. In the second and third trimesters, SCH patients continued to exhibit higher TC, TG, and LDL-c levels, but there was no significant difference in HDL-c levels [ 19 , 20 ].…”

“…For pregnant patients with hypothyroidism, clinical guidelines suggested that L-T4 replacement therapy should be given promptly to mitigate the risk of dyslipidemia and adverse neonatal outcomes [ 14 ]. Although observational studies have demonstrated that dyslipidemia has also been observed in SCH pregnant women [ 18 – 24 ]. A large cohort study involving 20,365 participants demonstrated that L-T4 treatment significantly reduced TC and LDL-c levels in SCH patients during the first trimester [ 91 ].…”

The application of new concepts of the assessment of the thyroid state to pregnant women

“…On account of the relevant studies being negative or conflicting (12,18,19), national colleges of obstetrics do not consider subclinical thyroid dysfunction to be a relevant entity (20, 21). Nevertheless, increasing numbers of pregnant women are having thyroid treatments (22) presumably in part on account of guidelines (23)(24)(25) and some positive trials concerning both associations of subclinical hypothyroidism with pregnancy outcomes and treatment of the thyroid state (26)(27)(28)(29).…”