Isolated maternal hypothyroxinemia (IMH) is a manifestation of thyroid hormone deficiency during pregnancy, which may affect fetal neurodevelopment and increase the risk of miscarriage, preterm birth, and gestational diabetes. However, uncertainties remain regarding its specific mechanisms, optimal treatment plan, and long-term effects. This paper summarizes the differences in thyroid hormone levels between pregnancy and non-pregnancy states. By reviewing relevant literature, we provide a comprehensive analysis of the disease's etiology, its impact on both mother and infant, and treatment strategies. The paper suggests that iodine deficiency and iron deficiency are the primary causes of isolated hypothyroxinemia during pregnancy. However, conclusive evidence regarding the association of factors such as placental growth factor with the disease is still lacking. At present, the negative effects of IMH on perinatal motor and neurodevelopment are relatively clear, but the adverse pregnancy events associated with it have not been conclusively confirmed, and the underlying pathological mechanisms remain insufficiently understood. Regarding treatment, the efficacy and timing of thyroid hormone replacement therapy remain controversial and require further investigation. This paper reviews the current state of research on IMH, aiming to raise awareness among clinicians, promote early identification and intervention, and reduce the occurrence of related adverse maternal and neonatal outcomes.