Definition of Neonatal lupus

Neonatal lupus: A lupus-like disease in a baby. This is due to the transfer through the placenta of lupus antibodies from the mother who has lupus to the fetus. (By lupus here is meant SLE -- systemic lupus erythematosus.)

Neonatal lupus can cause a decrease in red cells (anemia), white blood cells and platelets, and a skin rash. Problems can also develop in the electrical system of the baby's heart (congenital heart block). A pacemaker for the baby's heart may be needed in this setting. Neonatal lupus and congenital heart block are more common in newborns of mothers with SLE who carry antibodies referred to as anti-Ro (or SS-A) and anti-La (or SS-B).

It is wise for the newborn baby's doctor to be made aware, if the mother is known to carry these antibodies. Risk of heart block is 2%, risk of neonatal lupus is 5%.)

Neonatal lupus usually clears after six months of age as the mother's antibodies are slowly metabolized by the baby. See also: Lupus in pregnancy.