Ineffective therapy, underpowered studies, or merely too little, too late? Risk factors and impact of maternal corticosteroid treatment on outcome in antibody-associated fetal heart block.

It is estimated that 2% to 3% of pregnant women carry the anti-SSA/Ro antibody, which can be found in various autoimmune disorders, including Sjögren syndrome (SS), systemic lupus erythematosus, rheumatoid arthritis, and mixed connective tissue disorder.1,2 In addition, many women are asymptomatic carriers, with less than one third of antiSSA/Ro–positive women diagnosed with a rheumatological disorder preceding the discovery of advanced heart block in the fetus.3,4 Prospective studies have demonstrated that, in the absence of a previously affected pregnancy, the fetuses of these women bear up to a 3% risk of developing cardiac manifestations of neonatal lupus (NL), including cardiac conduction abnormalities, structural cardiac defects, and isolated cardiomyopathies.5–7 In women with a previously affected pregnancy, the recurrence rate of congenital heart block can reach as high as 17%.8,9