Thyroid dysfunction is one of the most common clinical problems among pregnant women. Before the onset of foetal thyroid function in mid gestation, the foetus is completely dependent on the maternal supply of thyroid hormones, which play a crucial role in the foetal growth and development. The increased requirement of thyroid hormones by approximately 50% during pregnancy is a challenge for the maternal thyroid glands. Our recent systematic review and meta-analysis showed that maternal thyroid dysfunction is associated with neurodevelopmental disorders, such as attention deficit hyperactivity disorder and epilepsy. However, the association between maternal and offspring thyroid dysfunction were only investigated in single studies. The major disadvantage of existing studies included limited sample size and unavailability of confounding variables. This project aims to evaluate the association between maternal and offspring thyroid dysfunction in an individual cohort of larger sample size, with appropriate adjustment for confounding factors. It is expected that the results may provide insights on the clinical practice in handling thyroid dysfunction in pregnant mothers and their offspring.