Neonatal lupus is an autoimmune disorder that presents at birth or within the first few months of an infant's life. It is different from systemic lupus erythematosus or discoid lupus erythematosus, forms of the disease that commonly affect adults and which do not clear up. A skin rash is the most common sign of neonatal lupus, though the condition can also cause liver and heart problems.
When a mother is pregnant with her baby, she can pass certain antibodies, anti-Ro, or anti-SSA, through the placenta to the developing fetus. These antibodies are the cause of neonatal lupus. The mother does not need to have any form of lupus in order to pass antibodies to her fetus, though about one third of women who have systemic lupus erythematosus have anti-Ro or anti-SSA antibodies.
The condition is extremely rare. Not every mother passes antibodies to her baby and fewer than ten percent of babies who receive the antibodies develop the disorder. About three percent of women with systemic lupus will have babies who develop the neonatal form of the disease. If one baby does develop neonatal lupus, it is more likely that future siblings will also develop the condition.
A red skin rash is the most visible symptom of neonatal lupus. In a majority of cases, the rash appears when the baby is born. Alternatively, the rash may appear after a few weeks in about a quarter of lupus cases. Sun exposure can make the rash look worse. It usually clears up within a few months as the infant's body clears itself of the antibodies. Having neonatal lupus does not increase the chances of a person developing lupus erythematosus as he gets older.
Neonatal lupus can cause other problems in addition to rashes. Some infants develop damage to their livers while others may develop thrombocytopenia. If a person has thrombocytopenia, his body does not produce enough platelets, which help the blood clot. Infants with thrombocytopenia can bruise easily. Like the rash, the liver problems and blood problems usually clear up within a few months.
An infant with neonatal lupus is also at risk of developing a congenital heart block. Unlike other symptoms, heart problems caused by the disorder will not clear up on their own as the antibodies leave the baby's system. The heart block alters the rhythm of a baby's heart beat and needs to be treated by a doctor. In some cases, the infant may wind up needing a pacemaker to fix the block. Fortunately, heart problems caused by lupus are even more rare than the condition itself.