Don't screen pregnant women for subclinical hyperthyroidism

...because the condition does not seem to adversely affect pregnancy, according to the findings of a recently published study.

Of almost 26,000 women screened for thyroid problems and delivering singleton infants, 433 had thyroid-stimulating hormone (TSH) values at or below the 2.5 percentile for gestational age and serum free thyroxine (fT4) levels of 1.75 ng/dL or less-which taken together are indicative of subclinical hyperthyroidism. The women with subclinical hyperthyroidism were more likely to be African-American and/or parous than white and/or nulliparous and were less likely to have hypertension during their pregnancies (adjusted OR 0.66, 95% CI; 0.44–0.98). No other pregnancy complication was increased in women with the condition. Nor was perinatal morbidity/mortality.

Casey BM, Dashe JS, Wells CE, et al. Subclinical hyperthyroidism and pregnancy outcomes. Obstet Gynecol. 2006;107:337-341.