. Author manuscript; available in PMC: 2022 Sep 1.

Published in final edited form as: Nat Rev Endocrinol. 2022 Jan 4;18(3):158–171. doi: 10.1038/s41574-021-00604-z

Table 1 |.

Current US recommendations for treatment of thyroid hypofunction in pregnancy

Laboratory data	ATA guidelines⁶	ACOC guidelines¹³
TPO antibody-negative and TSH >10 mlU/l	Treat with levothyroxine	Treat with levothyroxine only if free T₄ is low
TPO antibody-positive and TSH greater than the pregnancy-specific range (or >4 mlU/l)	Treat with levothyroxine	Treat with levothyroxine only if free T₄ is low
TPO antibody-positive and TSH >2.5 mlU/l but less than the pregnancy-specific reference range (or <4 mlU/l)	Consider treatment with levothyroxine	No treatment
TPO antibody-negative and TSH greater than the pregnancy-specific range (or >4 mlU/l) but <10 mlU/l	Consider treatment with levothyroxine	Treat with levothyroxine only if free T₄ is low
Isolated hypothyroxinaemia	No treatment	Not discussed

ACOG, American College of Obstetricians and Gynecologists; ATA, American Thyroid Association; TPO, thyroid peroxidase; TSH, thyroid stimulating hormone.