Thyroid Hormone Management in Pregnancy

Monitoring and Treatment

• The American College of Obstetricians and Gynecologists recommends levothyroxine treatment to return TSH to normal range, with dosage adjustments necessary for proper fetal neurologic development 3, 1
• Check TSH and free T4 every 4 weeks during the first half of pregnancy and at least once during the second half of pregnancy, with a target TSH in the lower half of the normal reference range 1
• Women with hypothyroidism should have their thyroid function optimized before conception, with a target preconception TSH below 1.2 mIU/L 2

Risks of Inadequate Treatment

• Untreated or inadequately treated maternal hypothyroidism increases the risk of preeclampsia, low birth weight, and impaired fetal neuropsychological development 2
• Maternal hypothyroxinemia has been associated with impaired fetal cognitive development and increased fetal mortality 2