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Prepregnancy TSH levels not linked to fecundity, pregnancy loss
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Thyroid-stimulating hormone levels of at least 2.5 mIU/L and the presence of antithyroid antibodies were not linked to fecundity, pregnancy loss or live birth in healthy fecund women with a history of pregnancy loss.
Marginal thyroid dysfunction is not likely to affect women with subclinical hypothyroidism or thyroid autoimmunity trying to conceive and achieve a live birth, according to researchers.
Sunni L. Mumford, PhD, an Earl Stadtman investigator in the epidemiology branch at Eunice Kennedy Shriver National Institute of Child Health and Human Development, and colleagues evaluated data from 1,193 women recruited from four medical centers in the United States between 2007 and 2011. Women were aged 18 to 40 years, had a history of pregnancy loss with no history of infertility and were actively trying to conceive.
Researchers sought to determine the links between prepregnancy TSH concentrations and thyroid autoimmunity with time to pregnancy, pregnancy loss and live birth.
Compared with participants with TSH levels less than 2.5 mIU/L, those with TSH levels of at least 2.5 mIU/L did not have a higher risk for pregnancy loss (RR = 1.15; 95% CI, 0.86-1.54) and were not less likely to have a live birth (RR = 1.01; 95% CI, 0.89-1.14). The presence of antithyroid antibodies did not increase the risk for pregnancy loss (RR = 0.9; 95% CI, 0.61-1.33) or lower the live birth rate (RR = 1.04; 95% CI, 0.9-1.2). Participants with TSH levels of at least 2.5 mIU/L and one previous pregnancy loss were not at greater risk for pregnancy loss compared with participants with TSH less than 2.5 mIU/L (RR = 1.13; 95% CI, 0.8-1.6). No differences were found for risk for pregnancy loss and live birth rate among participants with TSH levels of at least 2.5 mIU/L and those with TSH less than 2.5 mIU/L. The time to conceive was not longer among participants with TSH of at least 2.5 mIU/L compared with those with TSH less than 2.5 mIU/L (fecundability OR = 1.09; 95% CI, 0.9-1.31).
“Currently, the American Congress of Obstetricians and Gynecologists does not recommend screening of TSH in healthy, low-risk, asymptomatic patients, and our data support maintaining this guideline,” the researchers wrote. “Additionally, the cohort of patients in this study with thyroid antibodies did not have a higher risk of pregnancy loss compared to women without thyroid antibodies. These findings can be reassuring to both clinicians and women with subclinical hypothyroidism or thyroid autoimmunity.” – by Amber Cox
Disclosure: The researchers report no relevant financial disclosures.
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