Monitoring of thyroid function during pregnancy Thyroid disorders are one of the common diseases among women of reproductive age in China and are also common in women in the first half of pregnancy in China; hypothyroidism (or subclinical hypothyroidism/TPOAb positive) in pregnant women increases the risk of adverse pregnancy outcomes (e.g., preterm birth, low birth weight, miscarriage, stillbirth, increased incidence of gestational hypertension) and increases the risk of neurointellectual developmental impairment in the offspring, so thyroid monitoring during pregnancy is The monitoring of thyroid function during pregnancy is necessary. Screening for thyroid function during pregnancy is chosen before 8 weeks of gestation, preferably before pregnancy. The most common thyroid function abnormality in pregnancy is hypothyroidism, which includes clinical hypothyroidism (elevated serum TSH levels and decreased FT4 levels), subclinical hypothyroidism (elevated serum TSH levels and normal FT4 levels), and hypo-T4emia (normal serum TSH levels and decreased FT4 levels), which is commonly caused by autoimmune thyroiditis. immune thyroiditis. For women planning pregnancy, it is best to control serum TSH to <2.5mIU/L before considering pregnancy; for hypothyroidism during pregnancy, the TSH treatment goals are 0.1-2.5mIU/L in early pregnancy, 0.2-3.0mIU/L in mid pregnancy and 0.3-3.0mIU/L in late pregnancy; once the diagnosis of hypothyroidism is clear, treatment should be started immediately to achieve the treatment goals as soon as possible to Reduce adverse pregnancy outcomes. During pregnancy, thyroid hormone levels should be checked regularly, and thyroid function should be tested once a month during the first half of pregnancy, and the dose of L-T4 should be adjusted according to the control goal; serum thyroid function should be tested once at 26-32 weeks of pregnancy. For patients with subclinical hypothyroidism in pregnancy, those with positive TPOAb should receive L-T4 therapy with the same goals as those with clinical hypothyroidism; however, patients with TPOAb-negative subclinical hypothyroidism can be left untreated; the effects of simple hypotension on fetal development are not well understood and L-T4 therapy is not routinely used. The dose of L-T4 in hypothyroid pregnant women will gradually increase during pregnancy and reach a stable state around 20 weeks of gestation, so the dose of L-T4 should be reduced to pre-pregnancy level after delivery (L-T4 can be temporarily discontinued after delivery for those with normal thyroid function before pregnancy), and the TSH level should be rechecked 6 weeks after delivery to determine the treatment plan. Breastfeeding is very safe in hypothyroid women. Because the supplemented L--T4 is a nutrient in the body, the body does not secrete enough to replace the supplementary treatment, as long as the dose is appropriate safe and reliable.