Does Treating Subclinical Thyroid Disease During Pregnancy Improve Cognitive Outcomes in Children?

Subclinical hypothyroidism, hypothyroxinemia tx with levothyroxine did not impact IQ scores
Subclinical hypothyroidism, hypothyroxinemia tx with levothyroxine did not impact IQ scores

(HealthDay News) — Treatment for subclinical hypothyroidism or hypothyroxinemia before 20 weeks of gestation is not associated with better cognitive outcomes in children, according to a study published in the March 2 issue of the New England Journal of Medicine.

Brian M. Casey, M.D., from the University of Texas Southwestern Medical Center in Dallas, and colleagues screened women with a singleton pregnancy for subclinical hypothyroidism and for hypothyroxinemia before 20 weeks of gestation. Women were randomized to levothyroxine or placebo in separate trials: 677 women with subclinical hypothyroidism underwent randomization at a mean of 16.7 weeks of gestation and 526 with hypothyroxinemia were randomized at a mean of 17.8 weeks of gestation.

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The researchers found that the median IQ score of children at age 5 years was 97 and 94 in the levothyroxine and placebo groups, respectively, in the subclinical hypothyroidism trial (P = 0.71), and 94 and 91, respectively, in the hypothyroxinemia trial (P = 0.30). IQ scores were missing for 4 percent of children in each trial. No significant between-group differences were seen in either trial for any neurocognitive or pregnancy outcomes or for adverse event incidence.

"Treatment for subclinical hypothyroidism or hypothyroxinemia beginning between 8 and 20 weeks of gestation did not result in significantly better cognitive outcomes in children through 5 years of age than no treatment for those conditions," the authors write.

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