Umbilical dilatation may be associated with chromosomal abnormalities, in addition to maternal factors and the development of the abdominal body wall. During the tenth week of fetal life, the midgut collaterals begin to retreat into the abdominal cavity due to the increase in abdominal volume, a process that is completed by the 11th week at the latest, and failure of the bowel to return to the abdominal cavity results in the incomplete development of the surrounding abdominal wall, i.e., umbilical dilatation. Umbilical dilatation is a type of congenital abdominal wall defect. Umbilical dilatation is often associated with chromosomal abnormalities or malformations of other organs, such as trisomy 13, 18, and 21, and only a few umbilical dilatations are simple umbilical dilatation. On the maternal side, it is believed that early swelling and advanced age of the mother are risk factors for umbilical dilatation; maternal obesity increases the incidence of umbilical dilatation; and second-hand smoke also increases the risk of umbilical dilatation.