Results showed that both mRNA expression and protein expression of Dio1 were significantly decreased under preeclamptic conditions in rats' livers and remarkably upregulated after treatment with the antihypertensive drug, suggesting that the downregulated Dio1 expression was caused by preeclampsia; as a result, the metabolism of thyroid hormones can be affected which may lead to decreased hepatic T3 production. This evidence concerns the gene DIO1 and preeclampsia.