Which is the only immunoglobulin transported through the placenta to the fetus?

Correct option is B

Ans. (b) IgG
Sol. IgG is the only immunoglobulin that can cross the placenta, providing passive immunity to the fetus. This maternal IgG protects the newborn against infections during the early months of life until the baby’s own immune system develops.
Explanation of each option:
· (a) IgM – Incorrect. First antibody produced during an immune response but does not cross the placenta due to its large size.
· (b) IgG – Correct answer. It is the smallest immunoglobulin and the only one that crosses the placenta, providing passive immunity to the fetus.
· (c) IgH – Incorrect. Not a recognized immunoglobulin class.
· (d) IgD – Incorrect. Primarily involved in B-cell activation and does not cross the placenta.