Previous studies have demonstrated that maternal thyroid dysfunction is associated with a number of neurodevelopmental disorders, such as attention deficit hyperactivity disorder and epilepsy. However, the association between maternal thyroid dysfunction and other health outcomes in offspring were either investigated in single study, or not examined. One single study conducted in 998 maternal-child pairs in Canada demonstrated that maternal hypothyroidism was associated with increased risk of congenital heart disease (CHD) in offspring (OR=1.68; 95% CI: 1.02-2.78). Another retrospective cohort study showed that children born to mothers with hypothyroidism have increased risk of hypoglycemia (RR=2.9; 95% CI: 1.4-6.2) and total endocrine morbidity (RR=2.1; 95% CI: 1.2-3.8). It was also observed that offspring of mothers with subclinical hypothyroid during the third trimester of pregnancy had higher systolic blood pressure. It remains unclear if the above associations exist in other populations. Whereas, inconsistent findings were observed for the risk of diabetes in children born to mothers with various thyroid diseases. It is known that thyroid dysfunction in adults may affect a number of cardiometabolic traits. This project aims to evaluate the observational and causal association between maternal thyroid dysfunction and various cardiometabolic traits in offspring.