When a woman is pregnant, the level of thyroid hormone secretion will be affected by changes in hormone levels in the body and higher than normal, but if the patient is not aware of hyperthyroidism before pregnancy and cannot be screened in a timely manner, it may result in miscarriage, preterm labor, delayed development of the fetus, or even stillbirth, etc. At the same time, the chance of gestational hypertension in this period of time is also greater. With the popularization of nail function screening, some pregnant women have been found to have subclinical hypothyroidism or hypothyroidism without knowing it. Subclinical hypothyroidism or hypothyroidism in pregnant women may affect the intellectual development of the fetus, and may even cause serious intellectual disability after birth, and may also affect the development of motor coordination of the fetus. Hypothyroidism occurs during pregnancy and can easily be confused as a reaction to pregnancy because the early symptoms of hypothyroidism are insidious, with only symptoms such as fatigue and drowsiness, loss of energy, and memory loss. If a woman is planning to get pregnant, she should have her thyroid function checked 3 months before conception or pregnancy. Especially if there are abnormalities in her thyroid function, or if there is a history of thyroid disease in her family, and if she lives in iodine-deficient areas, she should pay special attention to monitoring the indicators of the thyroid gland under the guidance of her doctor. Be sure to normalize thyroid hormones and TSH before getting pregnant. For patients with previous hypothyroidism, subclinical hypothyroidism or Hashimoto’s thyroiditis, TSH needs to be controlled below 2.5 mIu/l before considering pregnancy. Pregnant women who have unexplained symptoms such as fatigue and weakness, less sweat and coldness, waxy skin, dry hair, sleepiness and drowsiness, loss of energy, memory loss, slow reaction time, abdominal distension and constipation, weight gain, anemia, etc., should consult a doctor as soon as possible for examination.