No Link Found Between Newborn Thyroid Function, Cognitive Development

Newborn thyroid function within the normal range was not associated with cognitive development or with maternal thyroid function, according to a recent study .

Researchers from Harvard Medical School and other sites in Boston studied children born between 1993 and 2003 at 34 weeks of gestation or older (n=500) to examine the relationship between thyroxine levels in newborns and first trimester maternal thyroid function and cognition in childhood.

The mean newborn T₄ was 17.6 mg/dL, according to the researchers. Levels were 1.07 mg/dL greater in girls (95% CI, 0.38-1.76) and 0.43 mg/dL greater in infants born after longer gestation (95% CI, 0.18-0.69).

When adjusted for maternal and child characteristics, higher newborn T₄ was associated with lower scores on the visual recognition memory test among infants aged 6 months (–0.5; 95% CI, –0.9 to –0.2), according to the researchers.

However, at age 3 years researchers did not find this association with scores on the Peabody Picture Vocabulary Test and the Wide Range Assessment of Visual Motor Ability test.

“In this sample from an iodine sufficient area, first trimester maternal thyroid function did not appear to affect a newborn’s thyroid function at birth, nor does lower neonatal thyroid function within the normal range impact a child’s cognition,” Elizabeth N. Pearce, MD, assistant professor of medicine at Boston University School of Medicine, said.

These results were unexpected; we look forward to the results of trials currently ongoing in the United States and Europe to better elucidate the relationship between mild maternal hypothyroidism and child cognition.

Source: Endocrinetoday