Associations between thyroid autoantibody status and abnormal pregnancy outcomes in euthyroid women

Abstract

We investigated whether thyroid autoantibody status influences pregnancy outcomes in euthyroid women, by comparing abnormal pregnancy outcome rates between those who tested positive for thyroid autoantibodies (Ab+) and those who tested autoantibody-negative (Ab-). Euthyroid pregnant women (n=7,641) underwent tests for serum thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb). The subjects were divided into 4 groups according to thyroid antibody status: TPOAb-/TgAb- (92.9%); TPOAb+/TgAb- (3.2%); TPOAb-/TgAb+ (2.0%); and TPOAb+/TgAb+ (1.9%). The incidence rates of the following abnormal pregnancy outcomes were compared among the 4 groups and analyzed by Fisher's exact test: gestational diabetes, gestational hypertension, placenta previa, placental abruption, premature rupture of fetal membrane (PROM), intrauterine growth restriction, fetal distress, fetal anomalies, stillbirth, preterm birth, and low birth weight. Among the 4 groups, there were no significant differences in age, gestational age, or in the incidence rates of abnormal pregnancy outcomes, except for PROM and low birth weight. The highest incidence rates for PROM and low birth weight were in the TPOAb-/TgAb+ and TPOAb+/TgAb+ subjects, respectively. TgAb positivity and TPOAb positivity were associated with PROM and low birth weight, respectively. Underlying factors that govern the association between thyroid autoantibodies and PROM and low birth weight require further investigation.

Thyroid antibodies and gestational diabetes mellitus: a meta-analysis

“…The synthesis meta-analysis showed no significant association between TgAb and GDM, with a pooled RR of 1.34 (95% CI 0.93-1.95). The meta-analysis of the three cohort studies (16,18,19) demonstrated results similar to the association between TPOAb and GDM risk (pooled RR 1.23, 95% CI 0.78-1.95; Table 1). For all of these meta-analyses, no statistically significant heterogeneity was found, and fixed-effect models were used.…”

“…In studies that included euthyroid women (9,10,15,19,20,24,25,28), the pooled RR of thyroid antibodies or TPOAb positive status on GDM incidence did not reach statistical significance (for thyroid antibodies, pooled RR 1.08, 95% CI 0.97-1.22; for TPOAb, pooled RR 1.06, 95% CI 0.94-1.20; Table 1; Fig. 3).…”

“…2). The meta-analysis of the 11 cohort studies (9,15,16,18,19,21,24,25,27,28) suggested that pregnant women with positive thyroid antibodies in the first trimester had no obvious risk of GDM compared with the reference group (pooled RR 1.07, 95% CI 0.96-1.19; Table 1; Fig. 2).…”

“…The synthesis meta-analysis showed a significant association between TPOAb and GDM risk with a pooled RR of 1.11 (95% CI 1.01-1.21). The meta-analysis of the eight cohort studies (9,16,18,19,21,24,25,27) suggested that compared with the reference group, TPOAb-positive status in the first trimester had no obvious impact on the risk of GDM in pregnant women (pooled RR 1.06, 95% CI 0.94-1.19; Table 1). No statistically significant heterogeneity was found, and fixed-effect models were used in the meta-analysis.…”

“…The prevalence of thyroid antibodies in pregnant women is approximately 10%-15% (8). In recent years, many epidemiologic studies have investigated the links between thyroid antibodies, including thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb), and risk of GDM (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28). However, these studies have apparently yielded conflicting results.…”