**Core Concept**
Children born to mothers with systemic lupus erythematosus (SLE) are at increased risk of congenital heart block due to maternal anti-Ro/SSA antibodies crossing the placenta and attacking fetal cardiac conduction tissue.

**Why the Correct Answer is Right**
Maternal anti-Ro/SSA and anti-La/SSB antibodies, commonly present in SLE, can cross the placenta and target the fetal cardiac conduction system, particularly the atrioventricular (AV) node. This leads to autoimmune-mediated damage of the AV conduction system, resulting in **complete heart block**. This is a well-documented association, with studies showing up to 10–20% of infants of SLE mothers develop congenital heart block, especially when antibodies are present in high titers.

**Why Each Wrong Option is Incorrect**
Option A: Atrial septal defect is a common congenital heart defect but is not specifically linked to maternal SLE or autoantibodies.
Option B: Tetralogy of Fallot is a cyanotic heart defect with a distinct developmental origin and no known link to maternal autoimmune disease.
Option C: Transposition of great vessels is a rare, structural anomaly unrelated to maternal SLE or autoantibody exposure.

**Clinical Pearl / High-Yield Fact**
In infants of SLE mothers, **anti-Ro/SSA antibodies** are the key risk factor for **congenital complete heart block**—a condition that may require permanent pacemaker implantation. Always screen for these antibodies in pregnant women with SLE.

✓ Correct Answer: D. Complete heart block