Consensus statements
- The American Society for Reproductive Medicine considers it reasonable to test infertile women trying to conceive and to treat SCH with levothyroxine to maintain a TSH less than 2.5 mIU/L and within the normal range. Women who have TAI and TSH greater than 2.5 mIU/L can be considered for treatment with levothyroxine.
- The Endocrine Society recommends levothyroxine in women with SCH who have TAI.
- The American Thyroid Association guideline recommends women with SCH who are undergoing IVF be treated with levothyroxine to achieve a TSH concentration less than 2.5mIU/L.
- The 2011 guidelines of the American Thyroid Association and the 2012 guidelines of the Endocrine Society recommended the specific reference ranges for TSH in the early, middle, and late stages of pregnancy as 0.1-2.5 mIU/L, 0.2-3.0 mIU/L, and 0.3-3.0 mIU/L, respectively.
- The American College of Obstetricians & Gynecologists recommend avoiding universal thyroid screening in pregnancy since “identification and treatment of maternal subclinical hypothyroidism has not been shown to result in improved pregnancy outcomes and neurocognitive function in offspring.”
Conclusion
The 2019 Cochrane Database states there are no clear conclusions regarding treatment with levothyroxine in euthyroid TAI or SCH because of the low quality of evidence reported. While TAI and SCH have been associated with pregnancy complications, there is no apparent benefit of levothyroxine in women with TAI or TSH levels between 2.5 and 4 mIU/L.
So, the conundrum is which preconception women to test and how to manage nonovert thyroid disease. For now, it is reasonable to obtain a serum TSH on all women desiring fertility, to treat SCH with levothyroxine to maintain TSH less than 2.5 mIU/L in the normal range, and to adjust levothyroxine accordingly throughout pregnancy.
Dr. Trolice is director of fertility at CARE – The IVF Center in Winter Park, Fla., and professor of obstetrics and gynecology at the University of Central Florida, Orlando. He has no disclosures. Email him at obnews@mdedge.com.