What is the cause of a vsd in a baby?

Unkown: The formation of the wall between the ventricles is late in cardiac development, but usually complete before the 12th week of pregnancy. The specific cause for a vsd is not well understood, but appears to be complex interaction of genes and gene modifiers.

This is a: Congenital defect and while associated with some birth defects often occurs spontaneously.

Multiple: A hole in the bottom two heart chambers (vsd) has many potential causes. Some happen spontaneously while others are associated with certain genetic and chromosomal anomalies. There is not one specific cause.