Gestational diabetes mellitus (GDM) is one of the most common disorders which occured during pregnancy. GDM is not only associated with short-term maternal and fetal adverse outcomes, but also related to a wide range of long-term consequences for both mother and child. The GDM and Its Consequences for mothers and offsprings (GDMCMO) aims to establish a cohort to follow both maternal and offsprings'short-term and long-term outcomes, including fetal malformations including congenital heart diseases, birth weight, preterm birth, caesarean section delivery, body growth and neurodevelopment after birth, obesity, type 2 diabetes and impaired insulin sensitivity and secretion, lung health and allergic diseases later in life for offspring, as well as future type 2 diabetes and cardiovascular risk factors for mother after delivery. Biological samples including blood and tissue samples of mothers and children are also collected during pregnancy and after delivery.