Maternal thyroid peroxidase antibodies during pregnancy: A marker of impaired child development?

Abstract

We recently reported that 5 year old children of women with antibodies against the enzyme thyroid peroxidase (TPO-Ab) during pregnancy, but normal thyroid function, are found to be at risk for impaired development (after correction for confounding variables such as maternal educational level or maternal depression). Until now the presence of maternal TPO-Ab during gestation was not considered to be harmful. The children of TPO-Ab antibody positive mothers however had an increased risk for low scores at the general cognitive scale of the McCarthy scales: O.R. = 10.5, 95% CI = 3 – 34. However, it might be questioned whether the scores of infant cognitive functioning at preschool age are not impaired by other factors which could not yet be taken into account.Therefore, in order to study if this relation between the mothers condition with regard to thyroid peroxidase during pregnancy and child development can also be found at an earlier age, we now assessed 240 infants at nine months with the Bayley scales. The first results show a significant difference on the motor scale. The group of 18 children whose mothers had elevated TPO-Ab titers during pregnancy had a significantly lower mean score than the children of TPO-Ab negative mothers (mean difference 11.5, 95% CI 3 – 19). Children of TPO-Ab antibody positive mothers also had lower scores on the mental and nonverbal scale (mean difference respectively 5.9 and 5.6), which did not reach significance levels. Moreover we found that the titer of TPO-Ab during gestation was of importance: only children of women who had elevated titers both at 12 and 32 weeks' gestation (the titer declines physiologically during pregnancy) had significantly different scores.This study indicates again that elevated titers of maternal thyroid peroxidase antibodies during pregnancy may be seen as a risk factor for developmental delay of the children.