[Multifactorial analysis of effects of mothers' autoimmune thyroid disease on their infants' intellectual development].

OBJECTIVE: To analyze factors relevant to retarded intellectual development in infants born to mothers with autoimmune disease of thyroid. METHODS: All the term newborns born to mothers with autoimmune thyroid disease (selection criteria) without asphyxia in all county, city, and provincial hospitals in Zhejiang province (except for Ningbo City) from July 2001 to June 2003 were enrolled through Zhejiang provincial neonatal disease screening network system. The control group was consisted of the neonates who were born to mothers without thyroid disease in these hospitals during the same period. Heel capillary blood samples were collected from the neonates older than 3 days in local hospitals and sent to the center of Zhejiang provincial neonatal disease screening network system. TSH levels were measured by Time Difference Fluorescent Analysis Device (1420 II type, EGG Company, US). If the level of TSH was higher than 9 mU/L, their mothers were called back to the center with their infants within 3 days. If the level of TSH was normal, they were called back to hospitals at age of 28 - 35 days of infants. The pattern of maternal thyroid disease, duration, thyroid function, the history of maternal drug administration, maternal age, gestational age and body weight of the neonates were recorded. The neonatal and maternal serum thyroid function tests were re-performed and the serum TPOAb, TGAb, TRAb and TSAb levels in both neonates and their mothers were measured as well. A 1-year follow-up study was done and all these subjects were investigated by means of Gesell development schedules by special investigators at the age of 1, 3, 6 and 12 months. The results were expressed as developmental quotient. Case-sectional study was performed. Statistical analyses were conducted using SPSS software. The multiple logistic regression analysis was used to analyze factors which might have effect on infantile personal-social ability, adaptive ability, gross motor ability or the fine-motor ability. One-way ANOVA was used to compare those five subfields ability followed by LSD multiple comparisons and Dunnet's C test was used when variances were not equal. Correlation analysis was used to compare the anti-thyroid antibody between neonates and their mothers. RESULTS: Poor personal-social ability, adaptive ability, gross motor ability and fine motor ability of infants born to mothers with autoimmune thyroid diseases were found as compared to the infants born to healthy mothers (P < 0.01). Moreover, the infants born to mothers with Hashimoto's thyroiditis had significantly poorer fine motor ability and adaptive ability than those born to mothers with Grave's disease (P < 0.05). The Spearman correlation coefficients of TPOAb, TGAb, TRAb and TSAb were 0.636, 0.574, 0.619 and 0.473, respectively, and all the P values were lower than 0.01.The multifactor logistic regression analysis showed that infantile TPOAb levels and maternal TRAb levels were associated with infantile personal-social ability, adaptive ability, and gross motor; while maternal TPOAb levels and thyroid function during gestation were associated with infantile fine-motor ability (P < 0.05). CONCLUSION: Maternal autoimmune thyroid diseases during pregnancy had adverse effects on intellectual development of infants. The maternal levels of TPOAb, TRAb and thyroid status were associated with the infantile personal-social ability, adaptive ability, gross motor and fine motor development. In order to reduce the effect on infant, it is necessary to treat adequately the maternal autoimmune thyroid diseases during pregnancy.