Mild thyroid dysfunction in pregnancy and children’s educational performance

Thyroid dysfunction is a common endocrinological problem during pregnancy, as 0.2% to 0.6% of pregnancies involve overt hypothyroidism (thyroid stimulating hormone concentrations exceeding reference intervals and free thyroxine concentrations below reference intervals) and an additional 3.5% to 18.0% of pregnancies are affected by subclinical hypothyroidism (elevated thyroid stimulating hormone concentrations but normal free thyroxine concentrations).1 Untreated overt hypothyroidism increases the risk of difficulty conceiving and of many adverse obstetrical and child outcomes, including impaired neuropsychological development.2 The consequences of subclinical thyroid dysfunction, especially with regard to cognitive outcomes for the child, are not that well established.2

A growing number of observational studies describe small but somewhat worrisome associations between mild maternal thyroid underfunction during pregnancy and juvenile cognitive development problems.2

In this issue, Nelson and colleagues (doi:10.1136/bmj.k452) present study assessing maternal thyroid function tests during early pregnancy and the school attainment of children from 54 months to 15 years of age drawn from the prospective Avon Longitudinal Study of Parents and Children birth cohort.3 In this well researched cohort of 4461 mother-child pairs collected …