How does hyperthyroidism affect pregnancy?
Uncontrolled hyperthyroidism has many effects. It may lead to preterm birth (before 37 weeks of pregnancy) and low birthweight. Some studies have shown an increase in pregnancy-induced hypertension (high blood pressure of pregnancy) in women with hyperthyroidism. A severe life-threatening form of hyperthyroidism, called thyroid storm, may complicate pregnancy. This is a condition in which there are extremely high levels of thyroid hormone that can cause high fever, dehydration, diarrhea, rapid and irregular heart rate, shock, and death, if not treated. Medications to treat hyperthyroidism may affect the fetus and newborn. Some medications may be associated with birth defects. It is not clear if anti-thyroid medications cause hypothyroidism (low levels of thyroid) in the fetus and newborn. Neonatal hyperthyroidism may occur in about 1 percent of newborns. Although most cases are temporary and do not cause problems for the baby, careful monitoring of the baby is important.
