Basedow’s disease is relatively common in women in their 20s and 30s. It is important for female patients to consult their doctors when planning pregnancy and childbirth.
For Basedow’s disease patients who are pregnant, it is vital that thyroid hormones are kept within a normal range. If thyroid hormone levels remain high during pregnancy, women face an increased risk of premature birth and miscarriage. For safe pregnancy and childbirth, thyroid hormone levels must be returned to normal levels in advance.
The main treatments for Basedow’s disease are oral administration of antithyroid drugs (mercazole or Thiuragyl/propacil) or inorganic iodine. Since there is a small possibility that taking mercazole in early pregnancy may affect embryos, patients who wish to become pregnant need to consult with their doctors in advance to plan appropriate treatment. If Basedow’s disease is severe, surgery may be performed at an early stage before pregnancy. For patients who can wait at least one year before pregnancy, treatment may be switched to isotope therapy.
In late pregnancy, if a patient’s thyroid is functioning normally and Basedow’s disease is stable and requires no medication, childbirth requires no special medical accommodations. The patient can have her baby where she is comfortable.
Thyroid-stimulating antibodies (TRAb and TSAb) characteristic of Basedow’s disease often decrease during pregnancy. However, if the levels of these antibodies remain high even in late pregnancy, they may stimulate the fetus’s thyroid gland through the placenta. These antibodies disappear from the baby’s body in approximately 1 month after birth. During this period, treatment may be needed for the infant. In this case, we recommend that the mother give birth in a hospital with a neonatology department.
In general, patients receiving oral Thiuragyl/propacil can breastfeed without restriction. Low doses of mercazole cause no harm. However, if the dosage is high, then intervals between breastfeeding need to be extended. In some cases, feeding the infant both breast milk and formula is the best option. Since iodine concentrates in breast milk, women who breastfeed their children are not given inorganic iodine.
Because Basedow’s disease tends to worsen after childbirth, it is important to regularly visit the hospital and receive appropriate treatment.
Some cases of hyperthyroidism in early pregnancy are not caused by Basedow’s disease. For these women, hyperthyroidism is due to a hormone produced by the placenta (human chorionic gonadotropin: hCG). The concentration of this hormone decreases in the second trimester of pregnancy, and the hyperthyroidism resolves on its own.