Abnormal thyroid hormone levels during pregnancy may increase the risk of preschool boys’ behavioural problems

Thyroid hormones are crucial for normal development of a baby’s brain and nervous system. During the first trimester a baby depends on its mother’s supply of thyroid hormone, which comes through the placenta. Levels of maternal thyroid hormones, including thyroid stimulating hormone (TSH) and free thyroxine (FT4), change dynamically during pregnancy, and both high and low maternal thyroid hormone levels can affect children’s behavioural development.

“Our findings highlight the significance of close monitoring and management of maternal thyroid function during pregnancy,” said Kun Huang, of the Anhui Medical University in Anhui, China. “This research presents a new perspective in early intervention of children’s emotional and behavioural problems.”

The researchers studied 1860 pairs of mothers and their children from the Ma’anshan Birth Cohort in China. The researchers repeatedly measured thyroid hormone levels in the first, second and third trimesters of pregnancy. The researchers followed up with the families when the children were 4 years old and had them fill out a checklist to evaluate their behavioural problems.

The researchers found boys born to mothers with high thyroid hormone levels during pregnancy were more likely to be withdrawn, have behavioural problems and be anxious or depressed. Moderate and low thyroid hormone levels were associated with aggressive behaviour in preschool boys.