In 155 women with systemic lupus erythematosus, there were no significant differences in the rates of fertility or adverse fetal outcome between the 47 (30%) with serum anti-SS-A antibody and the 108 without anti-SS-A, except in the frequency of congenital heart block. This complication occurred in 6 of 96 pregnancies in women with anti-SS-A and was associated with high-titer maternal antibody. The overall risk of a woman with lupus having an infant with congenital heart block was estimated to be 1:60, but the risk was considerably higher (1:20) if anti-SS-A antibody was present.