A National Institutes of Health (NIH) study suggests there is no benefit to treating mildly low thyroid function in pregnant women.
Researchers tested the thyroid hormone levels of more than 97,000 women at 15 centers from October 2006 to October 2009. The women had not yet reached their 20th week of pregnancy.
The women were screened for higher levels of thyroid stimulating hormone (TSH) and normal levels of thyroxine (T4), a thyroid hormone, as well as lower levels of T4. Elevated TSH and low T4 are both indicators of potentially reduced thyroid function, according to an NIH press release.
Subclinical hypothyroidism during pregnancy has been linked with impaired fetal neurological development and higher risk of preterm birth and miscarriage, NIH said. Other studies have found that even slightly low thyroid function could affect cognitive development in newborns and lead to a greater chance of complications during pregnancy and birth.
However, the study did not find a variance in cognitive functioning in children who were born to mothers with subclinical hypothyroidism who took medication during pregnancy and children whose mothers were not treated for subclinical hypothyroidism, NIH said. No variance was found for preterm birth rate, stillbirth, miscarriage and gestational diabetes.
“Our results do not support routine thyroid screening in pregnancy since treatment did not improve maternal or infant outcomes,” Dr. Uma Reddy of the NICHD Pregnancy and Perinatology Branch and author of the study, said in the news release.
