1. Why should thyroid function be monitored before pregnancy? High incidence: Thyroid disease is the second most common disease in the endocrine field, with a high incidence rate, 6-10 times higher in women than in men, and the incidence rate has climbed rapidly in recent years. Hazards of abnormal thyroid function: Abnormal thyroid function can lead to female infertility, miscarriage, premature birth, fetal malformations, and decreased intelligence in children: (1) Infertility: Women with abnormal thyroid function tend to be more prone to menstrual disorders, abnormal development of the reproductive system, and infertility. Thyroid disorders can cause menstrual disorders and abnormal ovulatory function in women, which makes it difficult to get pregnant. The presence of some antibodies to the thyroid gland may cause miscarriage and increase the chances of infertility, while such women, with a poor endometrial environment, are more likely to have miscarriages. (2) Fetal intelligence decline: thyroid health is related to the IQ of the next generation, and hypothyroidism in pregnant women can cause fetal brain development disorders, resulting in a 6 to 8-point drop in IQ of the offspring, especially during early pregnancy. Therefore, for the sake of the IQ of the next generation, it is important to pay attention to thyroid health. According to statistics, nearly 98% of hypothyroid patients worldwide are unaware that they have the disease. Mothers who develop hypothyroidism during pregnancy have children with significantly lower mental development and motor skills than children whose mothers have normal thyroid hormone levels. (3) Birth defects: Women with thyroid disease are more likely to give birth to offspring with heart, kidney or brain abnormalities, cleft lip, cleft palate, and polydactyly. 2. How to monitor thyroid function? The basic tests include TSH, FT3, FT4, TPOAb, and if necessary, a complete set of thyroid function tests plus antibody measurements, and if necessary, thyroid ultrasound. 3. What is the goal of thyroid function monitoring? Once the disease is diagnosed, you need to go to the endocrinology department of a regular hospital, and you can choose to get pregnant after effective treatment before pregnancy. For young patients in general, no signs and symptoms of abnormal thyroid function and TSH, T3 and T4 in normal range are sufficient. For patients with infertility or recurrent miscarriage, it is better to control TSH between 0.4-2.5mIU/L.