Effects of Maternal Iodine Deficiency in Women with Mild Thyroid Dysfunction During Early Pregnancy on Mental and Motor Growth of Their Offspring During Levothyroxine Treatment

The relationship between maternal thyroid function and intellectual development of offspring is controversial. Iodine may be an important confounding factor. This study investigated whether maternal iodine status could affect the efficacy of levothyroxine (LT4) treatment during early pregnancy on the intellectual growth of progeny.This prospective study divided participants into two groups; the normal iodine group included 53 mother–child pairs and the low iodine group included 60 mother–child pairs (urinary iodine concentration (UIC) ≥ 150 µg/L and UIC 0.05). 3) In comparison to the normal group, LT4 treatment on TPOAbs during pregnancy could not improve the MDI of the offspring, regardless of whether the iodine nutritional status was normal or not (P < 0.001, P = 0.047, respectively). These findings suggest that concurrent assessment and optimization of both thyroid function and iodine status during early pregnancy may be essential for maximizing offspring intellectual development.