Thyroid autoantibodies in pregnancy are associated with hypertensive disorders of pregnancy: Ma'anshan Birth Cohort Study

Summary Objective Hypertensive disorders of pregnancy (HDP) have been associated with adverse health outcomes for both mothers and children. Previous studies examining associations of maternal thyroid autoantibodies with HDP indicate conflicting results. The objective of this study was to examine associations of maternal thyroid autoantibody positivity in the first and the second trimesters with the risk of HDP. Design, Participants and Measurements In the Ma'anshan Birth Cohort study, a population‐based prospective study in China, a total of 3474 pregnant women were enrolled between May 2013 and September 2014. Thyroid autoantibodies, including antithyroperoxidase autoantibody (TPOAb) and antithyroglobulin autoantibody (TgAb), as well as thyroid function tests, were measured in both the first and the second trimesters in 2893 pregnant women. Multivariate logistic regression analyses were conducted to calculate the odds ratio (OR) and 95% confidence interval (CI) for the associations between thyroid autoantibodies and HDP. Results Multivariate logistic regression analyses showed that TPOAb positivity in the first trimester was associated with a 1.80 (95% CI = 1.17‐2.78) increased odds of HDP after adjustment for confounders, which was mainly due to an increased risk of gestational hypertension (OR = 1.93, 95% CI = 1.17‐3.18). In addition, TgAb positivity in the first trimester was associated with a higher risk of HDP (OR = 1.78, 95% CI = 1.16‐2.73) after adjustment for confounders, which was mainly due to an increased risk of gestational hypertension (OR = 1.89, 95% CI = 1.15‐3.11). These associations were also seen among euthyroid women. Women with positive TPOAb in the second trimester seemed to have a higher risk of gestational hypertension (OR = 1.87, 95% CI = 1.02‐3.43) after adjustment for confounders. However, among euthyroid women, TPOAb positivity in the second trimester was not associated with HDP. The TgAb status in the second trimester was not associated with HDP. Conclusions Our results show that TPOAb positivity and TgAb positivity in the first trimester are associated with an increased risk of HDP. These data demonstrate that these associations are even seen among euthyroid women.