Outcome and Growth of Infants Fetally Exposed to Heart Block-Associated Maternal Anti-Ro52/SSA Autoantibodies

OBJECTIVE: The purpose of this work was to analyze outcome with focus on growth in infants fetally exposed to heart block-associated maternal anti-Ro52/SSA autoantibodies and identify maternal factors other than the autoantibodies increasing the risk of fetal heart block. PATIENTS AND METHODS: Thirty-two pregnancies in 30 anti-Ro52-positive mothers were included. Seven fetuses developed second-degree or third-degree atrioventricular block, 8 developed first-degree atrioventricular block, and 17 had normal atrioventricular conduction, as diagnosed by using Doppler echocardiography. Three of 6 surviving fetuses with second-degree or third-degree atrioventricular block received treatment with fluorinated steroids. Two fetuses with second-degree atrioventricular block converted to first-degree atrioventricular block without any signs of progression during the study period. Maternal and longitudinal infant data were collected from planned neonatal follow-up and childhood health records from birth to 12 months of age in 31 survivors. RESULTS: Women giving birth to infants with prenatal second-degree or third-degree atrioventricular block were older and with higher parity than those with first-degree atrioventricular block or normal atrioventricular conduction. Second-degree or third-degree atrioventricular block pregnancies were <40 completed weeks, whereas pregnancies with first-degree atrioventricular block or normal atrioventricular conduction had a normal duration. Fetuses with second-degree or third-degree atrioventricular block were retarded by -0.98 +/- 0.77 SD in weight at birth and did not show any catch-up during infancy. In contrast, fetuses with first-degree atrioventricular block or normal atrioventricular conduction had a weight reduction of -0.51 +/- 1.01 SD with a catch-up during the first months after birth. CONCLUSIONS: This report documents that newborns with autoantibody-mediated second-degree or third-degree atrioventricular block are retarded in growth, with no catch-up during infancy, whereas fetuses with first-degree atrioventricular block or normal atrioventricular conduction have a normal growth soon after birth. Increased maternal age and/or parity seem to carry an increased risk for fetal heart block.