In pregnancy, how much should levothyroxine dose be adjusted for most patients?

During pregnancy, there is an increased demand for thyroid hormones due to the physiological changes that occur as the fetus develops. The production of thyroid hormone is stimulated by elevated levels of human chorionic gonadotropin (hCG) early in pregnancy, and also by the increased requirements of the growing fetus, especially during the second and third trimesters.

As a result, women who are already on levothyroxine therapy typically need to increase their dose during pregnancy to maintain appropriate levels of thyroid hormones. An adjustment of 25-50% is often recommended; this ensures that both the maternal and fetal needs are met, as hypothyroidism during pregnancy can lead to complications such as fetal development issues and adverse outcomes.

Monitoring thyroid function throughout the pregnancy is also essential, as it allows for dose adjustments to ensure that TSH levels remain within the appropriate range for optimal health of both the mother and the developing fetus.