Association between thyroid hormone parameters during early pregnancy and gestational hypertension: a prospective cohort study

OBJECTIVE: Thyroid dysfunction may play a role in the development of gestational hypertension. However, this relationship remains unclear. This study was performed to evaluate the association between thyroid hormone parameters during early pregnancy and gestational hypertension. METHODS: Women with singleton pregnancies were recruited into this prospective cohort study at 9 to 13 gestational weeks, and their serum thyroid-stimulating hormone, free thyroxine, and free triiodothyronine concentrations were measured using electrochemiluminescence immunoassays. In total, 1226 participants were included in the final analysis. RESULTS: Of the 1226 participants, 81 subsequently developed gestational hypertension (overall incidence of 6.6%). Compared with women with euthyroidism, both pregnant women with hypothyroidism and those with subclinical hypothyroidism had an increased risk of gestational hypertension (adjusted odds ratio [OR], 3.61; 95% confidence interval [CI], 1.52–8.57 and OR, 2.24; 95% CI, 1.06–4.72, respectively). When the thyroid-stimulating hormone and free thyroxine concentrations were analyzed by quintiles, the women in the highest thyroid-stimulating hormone quintile had a higher risk of gestational hypertension (adjusted OR, 4.22; 95% CI, 1.78–9.05) than the women in the middle quintile. CONCLUSION: Our results suggest that hypothyroidism, subclinical hypothyroidism, and a high thyroid-stimulating hormone concentration during early pregnancy are risk factors for gestational hypertension.