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

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.

Impact of maternal thyroid autoantibodies positivity on the risk of early term birth: Ma'anshan Birth Cohort Study.

PURPOSE: We aim to investigate associations of maternal serum anti-thyroperoxidase autoantibody (TPOAb) with duration of gestation. We aim to investigate whether maternal TPOAb positivity is associated with the risk of premature or early term birth. METHODS: This was a prospective birth cohort study performed in an iodine sufficient area of China. Serum samples were collected from 2931 women at both the first and second trimesters of pregnancy. Thyrotropin (TSH), free thyroxine (FT4), and TPOAb levels were measured. Data on gestational age at birth was obtained from delivery records. RESULTS: The prevalence of early term birth was 23.8%, while the prevalence of premature birth was 4.2%. The prevalence of TPOAb positivity was 12.1% in the first trimester and was 7.2% in the second trimester. Gestational age at birth was inversely associated with lgTPOAb both in the first trimester (ß, -0.283, 95% CI -0.408, -0.158; P < 0.001) and in the second trimester (ß, -0.174, 95% CI -0.319, -0.030; P = 0.018), after adjustment for potential confounding factors. There was a positive association of TPOAb positivity with the risk of early term birth both in the first (OR = 1.691, 95% CI 1.302, 2.197) and second trimesters (OR = 1.644, 95% CI 1.193, 2.264), after adjustment for potential confounding factors. TPOAb positivity in the second trimester was associated with a 1.863-fold higher risk of premature birth (OR = 1.863, 95% CI 1.009, 3.441), after adjustment for potential confounding factors. CONCLUSIONS: Our results show that TPOAb is associated with shorter duration of gestation and with higher risk of premature and early term birth.