Which immunoglobulin crosses the placenta?

Answer and explanation

Correct answer: A. IgG

  1. Step 1: IgG is transported across the placenta by the neonatal Fc receptor. Answer: IgG. Why not the others: IgM is too large, IgA is secretory and IgE binds mast cells.

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Which immunoglobulin crosses the placenta? | USMLE Step 1