Hashimoto’s thyroiditis 桥本氏甲状腺炎 is primary hypothyroidism caused by an autoimmune disease. Hashimoto’s thyroiditis occurs in pregnancy in approximately the same ratio as it occurs in the general female population.
Thyroid hormones play a crucial role in pregnancy and the development of the brain and nervous system of the fetus. The fetus is dependent on thyroid hormones from the maternal circulation through the placenta for the first three months of pregnancy. The fetus’ own thyroid takes over full function around 20 week’s gestation. Two hormones of pregnancy, human chorionic gonadotropin(HCG) and estrogen cause an increase in the measured thyroid hormones of pregnancy and may lead to a slight enlargement of the thyroid.
Symptoms of hypothyroidism in pregnancy are the same as for others:
- extreme tiredness
- cold intolerance
- problems with memory, concentration
- muscle cramps
Like Primary hypothyroidism, Hashimoto’s thyroiditis in pregnancy, an autoimmune disease is the causative factor. If left untreated there can be severe consequences for the mother and the infant, such as:
- Low birthweight
- And (rarely) in the mother, congestive heart failure.
Once diagnosed, treatment includes only using levothyroxine (T4) throughout the pregnancy. Testing will probably include thyroid hormone levels and antibody titres every 6 to 8 weeks.
NIH (n.d.) Thyroid Disease and Pregnancy. National Institute of Diabetes and Digestive and Kidney Diseases