TSH (thyroid-stimulating hormone) 4.3 μIU/L in early pregnancy is an abnormal phenomenon,which needs to be analyzed in combination with other thyroid indicators. According to China’s 2019 guidelines for the diagnosis and treatment of thyroid disease in pregnancy and postpartum, there are physiological changes in the thyroid gland during pregnancy, and it is recommended to establish a pregnancy-specific reference range for serum thyroid indicators.If pregnancy- and kit-specific TSH reference ranges are unavailable, 4.0 mIU/L can be used as the cutoff value for the upper limit of TSH in early pregnancy.Therefore, 4.3 mIU/L TSH in early pregnancy belongs to the high side, and is abnormal. Clinical hypothyroidism in pregnancy is diagnosed when TSH > upper limit of reference range in pregnancy and free T4 < lower limit of reference range in pregnancy. Clinical hypothyroidism in pregnancy impairs the neurointellectual development of the offspring and increases the risk of adverse pregnancy outcomes, including preterm labor, low birth weight, stillbirth, and miscarriage, and increases the risk of hypertensive disorders of pregnancy. Clinical hypothyroidism in pregnancy may be treated with oral levothyroxine sodium tablets to control TSH to 1/2 of the pregnancy-specific reference range, or less than 2.5 mIU/L. Consider subclinical hypothyroidism in pregnancy if TSH is > upper limit of the pregnancy-specific reference range and free T4 is within the pregnancy-specific reference range. Abnormal thyroid function during pregnancy requires prompt medical attention, and the use of medication in conjunction with other indicators can reduce the risk to both the mother and the fetus.