**Core Concept**
The first antibody produced by a newborn is an example of passive immunity, which is transferred from the mother to the child through the placenta and breast milk. This process provides the newborn with immediate protection against infections until its own immune system matures.

**Why the Correct Answer is Right**
The correct answer is IgG, which is the only antibody that can cross the placenta from mother to fetus. IgG antibodies are produced in response to infections and vaccinations, and they provide long-term immunity against specific pathogens. The presence of IgG antibodies in the newborn's circulation is crucial for protecting against infections, especially in the first few months of life.

**Why Each Wrong Option is Incorrect**
**Option A:** IgA is an antibody that provides mucosal immunity and is found in high concentrations in the respiratory, gastrointestinal, and genitourinary tracts. It is not the first antibody produced by the newborn.
**Option B:** IgM is the first antibody produced in response to an infection, but it is not the first antibody produced by the newborn. IgM is not able to cross the placenta from mother to fetus.
**Option C:** IgE is an antibody that plays a key role in allergic reactions and parasitic infections. It is not the first antibody produced by the newborn.

**Clinical Pearl / High-Yield Fact**
Newborns receive IgG antibodies from their mothers through the placenta, which provides them with immediate protection against infections. This is why newborns are not typically vaccinated until they are at least 2 months old, allowing the maternal IgG antibodies to wane and the infant's own immune system to mature.

**Correct Answer:** D. IgG.