Maternal hypothyroxinaemia in early pregnancy and problem behavior in 5 year-old offspring

Introduction: There is evidence, though not consistent, that offspring born to mothers with subtle decreases in thyroid function early in their pregnancies may be at risk of cognitive impairments and attention problems. However, other types of problem behavior have not been addressed thus far. We tested whether maternal thyroid function in early pregnancy is associated with several types of problem behavior in offspring at age 5-6 years. Methods: This was a longitudinal study that included the data of 2000 mother-child pairs from the Amsterdam Born Children and their Development study. At a median gestational age of 12.9 (interquartile range: 11.9-14.1) weeks, maternal blood was sampled for assessment of free T4 and TSH. Overall problem behavior, hyperactivity/ inattention, conduct problems, emotional problems, peer relationship problems and prosocial behavior were measured at age 5-6 years using the Strengths and Difficulties Questionnaire, which was filled out by both parents and teachers. Results: Maternal hypothyroxinaemia <5th percentile was associated with a 1.70 (95% confidence interval (CD: 1.01-2.86) increased odds of teacher-reported hyperactivity/inattention after adjustment for confounders. By increasing the cut-off level to