For patients with hyperthyroidism (commonly known as hyperthyroidism) or hypothyroidism (commonly known as hypothyroidism), there are usually symptoms, and it is a disease that belongs to the endocrinology department that needs to be treated. Patients with hyperthyroidism will have rapid heartbeat, trembling, excessive sweating, inability to tolerate heat, insomnia, weight loss, loose stools and other clinical manifestations, the typical manifestation is the hands raised flat with eyes closed when there is finger trembling, failure to control hyperthyroidism patients in the occurrence of high blood pressure during pregnancy, heart failure will be greater than the normal population. Hypothyroidism is characterized by fatigue, constipation, chills, muscle cramps, swelling, dry skin, and hair loss. Hypothyroidism patients who do not receive systematic treatment and become pregnant directly will have an increased chance of miscarriage and fetal neurodevelopmental abnormalities. Whether it is hyperthyroidism or hypothyroidism, it is necessary to undergo systematic examination and treatment in the endocrinology department, as far as possible to control the thyroid hormone in the normal level of pregnancy, or during pregnancy, if necessary, can also be considered to use medication to control through the gestation period. There is a clinical condition called subclinical hypothyroidism, which means that TSH is elevated and free T4 is within the normal range. The definition of subclinical hypothyroidism is about 5% of the population. Two observational studies in 1999 found that newborns born with subclinical hypothyroidism had lower IQ than newborns with normal thyroid function. However, this was the conclusion of an observational study (Levels of Evidence II-2 and II-3), and the conclusions are relatively unreliable. In a recent 2012 new randomized controlled study, it was found that supplementation with or without thyroid hormone in patients with subclinical hypothyroidism made no difference in the children’s cognitive functioning found at 3 years of age (Level of Evidence Level 1), and therefore, at present, neither the American College of Obstetricians and Gynecologists, nor the American Association of Clinical Endocrinologists Association do not recommend screening and treatment of thyroid function in the whole-pregnancy population, which is the most reliable conclusion as of now. Some years ago, many hospitals in China had carried out extensive screening of thyroid function, and were developing normal ranges of thyroid function in Chinese populations around the world, and gave pregnant women a diagnosis of subclinical hypothyroidism based on elevated TSH and normal free T4, and gave them eugenol for treatment. randomized controlled study results, it is probably possible to say no to such large population screening and diagnosis of subclinical hypothyroidism.