The incidence of Hashimoto’s disease is comparatively high in women. In addition, it is more common for Hashimoto’s disease patients to have normally functioning thyroids than suffer from hypothyroidism. Therefore, female patients are often diagnosed with Hashimoto’s disease for the first time when they are pregnant or receive infertility treatment.
If thyroid function remains low during pregnancy, it increases the risk of miscarriage and premature delivery. For safe pregnancy and childbirth, it is important to normalize hormone levels in advance through thyroid hormone replacement therapy.
Since thyroid hormones play an important role in fetal development and are provided maternally, demand for thyroid hormones increases during pregnancy. If patients wish to become pregnant, thyroid hormone replacement therapy may be started even if hormone levels are within the normal range. We use levels of thyroid-stimulating hormone (TSH) as an indicator. If thyroid hormone replacement therapy begins before pregnancy, the dosage will need to be adjusted after childbirth. Oral administration of thyroid hormone replacement medication (Thyradin S) does not affect babies. If patients realize they are pregnant, they should see a doctor as soon as possible without discontinuing oral medication.
Patients who are undergoing thyroid hormone replacement therapy and have normal thyroid function are free to give birth at the location of their choosing.
Following childbirth, the dosage of thyroid hormone replacement medication should be returned to the level used prior to pregnancy. Patients are welcome to breastfeed while continuing hormone replacement therapy. In patients with Hashimoto’s disease, thyroid function often changes after childbirth. Patients should regularly visit the hospital for monitoring after childbirth.