Research in Medicine

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 Background : Recent studies have shown normal thyroid function in infants whose mothers receive methimazole (MMI) during breast-feeding. This study evaluates the long-term effect of MMI on thyroid function and intellectual development of such children.

Methods : 82 children aged 48-86 months were studied. 42 children had been breast-fed while their thyrotoxic lactating mothers received daily doses of MMI 20-30 mg in the first, 10 mg in the second and 5-10 mg for additional 10 months of therapy. Thyroid function of infants remained normal during the one year of MMI therapy of their mothers. 40 other infants served as controls. Serum T4, T3, and TSH concentrations, urinary iodine, thyroid antibodies, intelligent quotient (IQ), verbal and functional (performance) components (Wechsler and Goodenough tests) were measured in all children of case and control groups.

Results : Height, weight, serum T4, T3, TSH and antithyroid antibody titers were not differed between children of case and control groups. The mean IQ was 107±17 vs 106±16 (Goodenough test) and 103±10 vs 103±16 (Wechsler test) for children of thyrotoxic mothers and control children, respectively. There was no difference in verbal and functional IQ and their components between children of thyrotoxic MMI treated mothers and control children.

Conclusion : Thyroid function and physical and intellectual development of breast–fed infants whose thyrotoxic lactating mothers were treated with MMI are normal at age 48 to 86 months.

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Background and Aim: 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. Material and Methods: 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. Results: The basic characteristics of children except maternal TSH and T4 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. Conclusion: This study showed that IQ level and cognitive performance in children who were born from sub clinical hypothyroid mothers are similar to control group. Keywords: Hypothyroidism Pregnancy, Intellectual Development, Cognitive Performance.