[Relationship between maternal hypothyroidism during pregnancy and intellectual development of offspring]

ABSTRACT

Children who were born from untreated hypothyroid mothers, have lower intelligence quotient [IQ] levels in school age in comparison with same age group. Nonetheless, the effect of hypothyroidism, especially subclinical form on fetal neuronal cell growth and subsequent imprints on intelligence and learning are unclear. This study was designed to evaluate intellectual development of children of mothers who had hypothyroidism, especially subclinical type during their pregnancies. In this historical cohort study, out of 441 hypothyroid women, 90 patients with 106 pregnancies were reviewed. 44 children were enrolled in this study. They were divided to case [N=25] and control groups [N=19] according to the maternal TSH level during pregnancy. For all children serum TSH and free T4 were measured by radioimmunoassay and urine Iodine concentration was assayed by acid digestion method. IQ level and cognitive performance of all children were also evaluated. The basic characteristics of children except maternal TSH and 14 were the same between two groups. The age range of children was 4-14.5 years. All laboratory parameters [TSH, free T4 and urinary iodine] were similar in two groups. There was no significant difference in IQ level and cognitive performance between two groups. Using Pearson correlation test, except mother education level and neonatal weight there were no relationship between variables and IQ level. This study showed that IQ level and cognitive performance in children who were born from sub clinical hypothyroid mothers are similar to control group