Levothyroxine (L-T4) in Fertility
Levothyroxine is the synthetic thyroid hormone preparation used to treat hypothyroidism, subclinical hypothyroidism, and thyroid autoimmunity in the fertility context. Clinicians dose levothyroxine to restore normal thyroid status and adjust targets based on whether the patient is attempting conception or already pregnant.
During pregnancy, thyroid hormone requirements typically increase by thirty to fifty percent in the first trimester to meet gestational demands. This requires early monitoring and proactive dose adjustment. Evidence for levothyroxine use in euthyroid women who are TPO-antibody positive with recurrent miscarriage is mixed: the 2019 TABLET trial found no benefit in this population, and the question remains under active investigation.
In restorative reproductive care, levothyroxine is initiated when TSH is elevated and adjusted through serial monitoring across the pregnancy. Thyroid evaluation is a routine component of the RRM infertility and recurrent-loss workup, with tighter TSH targets than non-fertility populations.
This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.