Ans. a). SLECongenital hea block is a rare disorder that occurs in about one out of 22,000 live bihs.In most cases, the cause is not known, but babies of mothers with lupus or other autoimmune diseases, or babies with congenital hea disorders, are at higher risk.Pregnant women who have autoimmune diseases, such as lupus or Sjogren's syndrome, are at an increased risk of having a baby with congenital hea block.Also, a tumor on the baby's hea can cause hea block.