(Shanghai, November 22, 2013) Thyroid disease is one of the common diseases among Chinese women of reproductive age and women in the first half of pregnancy. Thyroid disorders during pregnancy include clinical hypothyroidism (clinical hypothyroidism), subclinical hypothyroidism (subclinical hypothyroidism), positive thyroid autoantibodies (TPOAb), and hyperthyroidism during pregnancy, with prevalence rates of the above disorders among women in the first half of pregnancy being 0.6%, 5.27%, 8.6%, and 0.4%, respectively. This means that 1 in 10 expectant mothers may be affected by thyroid disease. Prof. Teng Weiping, Director of Endocrine Research Institute of China Medical University, and Prof. Duan Tao, Director of the First Maternity and Infant Healthcare Hospital affiliated with Tongji University, said: Abnormalities of thyroid function in women during pregnancy can cause adverse pregnancy outcomes such as miscarriage, preterm delivery, perinatal fetal death, and even affect the intellectual development of the offspring. Therefore, pre-pregnancy and early pregnancy thyroid function screening needs to attract widespread attention and focus of the whole society, early detection, diagnosis, and treatment of thyroid disorders not only benefits the health of women during pregnancy itself, but also safeguards the healthy development of the next generation. Thyroid disorders in pregnancy: a problem that should not be ignored Hypothyroidism in pregnancy is one of the factors causing neurointellectual damage in offspring. Early pregnancy, the first 12 weeks of pregnancy, is the first rapid development period of fetal brain development, but at this time, the fetus’s own thyroid function has not yet been established, and the thyroid hormones needed for fetal brain development are completely dependent on the mother’s supply. Prof. Teng Weiping said, “If the mother-to-be suffers from hypothyroidism during this period, i.e., the mother’s thyroid hormones are persistently at low levels, which cannot provide sufficient thyroid hormones for fetal brain development, it will affect fetal brain development and even cause irreversible damage.” In a screening of 1,268 pregnant women in China, 19 of them with pure subclinical hypothyroidism were studied for the intellectual and motor development of their offspring. The results showed that their intellectual and motor development scores were significantly lower than those of the control offspring. Another thyroid disorder in pregnancy, positive thyroid autoantibodies, greatly increases the incidence of miscarriage and preterm labor in pregnant women. A systematic review and meta-analysis of 31 studies conducted by Queen Mary University of London in the United Kingdom showed that the risk of miscarriage was three times higher in women with TPOAb-positive pregnancies. Their analysis of five studies found that the incidence of preterm labor was two times higher in TPOAb-positive women. Graves’ disease (toxic diffuse goiter) accounts for 85% of cases of hyperthyroidism in pregnancy (hyperthyroidism). Moderate and severe hyperthyroidism and uncontrolled symptoms are associated with significantly higher rates of miscarriage, hyperemesis gravidarum, preterm labor, microcephaly, and perinatal mortality. Screening for thyroid function indicators before pregnancy and in early pregnancy is imperative Because thyroid disease has no clinical symptoms in its early stages, and detection of the disease depends on laboratory tests, screening becomes very meaningful. A previous multicenter study of 2,899 pregnant women in China found that 81.6% of hypothyroidism patients and 80.4% of hyperthyroidism patients were underdiagnosed when screening for thyroid disease in high-risk pregnancies was adopted,” said Prof. Duan Tao. In contrast, studies and cost-effectiveness analyses showed that screening the entire gestational population was superior to no screening.” In 2012, China’s Guidelines for the Diagnosis and Treatment of Thyroid Diseases in Pregnancy and the Postpartum Period (2012) (hereafter referred to as the Guidelines) were officially launched, further promoting screening for thyroid disease in pregnancy. The Guidelines recommend that, in accordance with China’s national conditions, hospitals and maternal and child healthcare departments in China that are in a position to do so should be supported to conduct screening for thyroid disorders in women in early pregnancy, and the timing of the screening should be chosen before the eighth week of pregnancy. It is best to screen for thyroid indicators before pregnancy, and once the disease is diagnosed, effective treatment can be given before pregnancy before the opportunity to get pregnant, so as to maximize the health of the mother and child. During pregnancy, the synthesis and metabolism of thyroid hormones in the body are altered due to increased levels of estrogen and chorionic gonadotropin (HCG). The increased thyroid hormone fraction further inhibits the secretion of thyroid-stimulating hormone (TSH), which reduces serum TSH levels by 20-30%.The decrease in TSH levels occurs during the 8-14 weeks of gestation, with the lowest point of decline occurring during the 10-12 weeks of gestation. Meanwhile, serum free thyroxine (FT4) levels are elevated by 10-15% in early pregnancy compared to non-pregnancy. Because of the compromising effect of maternal immunity to the fetus, thyroid autoantibodies gradually decrease in titer after pregnancy, dropping to the lowest titer at 20-30 weeks of gestation, with a decrease of about 50%. The clinician can make a judgment about thyroid dysfunction in pregnancy and the need for treatment based on changes in the TSH, FT4, and TPOAb indices. Changes in these three indices are good predictors of thyroid disease in pregnancy. The Guidelines state that hospitals and maternal and child health departments with the conditions are supported to screen women in early pregnancy for thyroid disease, and the screening indexes are chosen to be serum TSH, FT4, and TPOAb. The Guidelines provide normative guidance on the treatment and monitoring of thyroid disease during pregnancy “Currently, a large number of potential patients in China are not diagnosed and treated in a timely manner, and the public also knows little about it.” Prof. Teng Weiping said, “The launch of the Guidelines gives normative guidance for clinical diagnosis, treatment, and monitoring of thyroid disorders in pregnancy and postpartum, which is conducive to improving the medical standard of thyroid disease treatment.” According to the recommendations of the Guidelines, the cost-effective and safe levothyroxine (L-T4) treatment should be preferred for clinical hypothyroidism during pregnancy. In pregnant women with clinical hypothyroidism, thyroid function should be tested every 4 weeks during the first half of pregnancy (1-20 weeks). Thyroid function should be tested at least once at 26-32 weeks of gestation. The L-T4 dose should be reduced accordingly after delivery and the maternal serum TSH level should be rechecked at 6 weeks postpartum to adjust the L-T4 dose. The treatment of subclinical hypothyroidism in pregnancy, treatment goals and frequency of testing are the same as those for clinical hypothyroidism, and different doses of L-T4 can be given according to the degree of TSH elevation. Pregnant women with positive thyroid autoantibodies who have normal thyroid function should have their serum TSH tested every 4-6 weeks during the first half of pregnancy and at least once more at weeks 26-32. If TSH is found to be above the pregnancy-specific reference range, L-T4 therapy should be given. Women with established hyperthyroidism should ideally consider pregnancy after thyroid function is controlled to normal. If a pregnant woman has Graves’ disease, or has a past history of Graves’ disease, she should be tested for thyroid-stimulating hormone receptor antibodies (Anti-TSHR) at 22-26 weeks of gestation, when titers are helpful in evaluating pregnancy outcome. Serum FT4 is the preferred indicator of hyperthyroidism during pregnancy, and FT4 and TSH should be monitored every 2-6 weeks in women treated with antithyroid drugs (ATDs). Hyperthyroidism in pregnancy (SGH) is associated with excessive placental secretion of HCG, and treatment is based on supportive therapy, correction of dehydration and electrolyte disorders, and does not advocate the use of antithyroid medications.