**Core Concept**
Indomethacin is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits prostaglandin synthesis by blocking the enzyme cyclooxygenase (COX). This action can have significant effects on fetal development, particularly during the third trimester.

**Why the Correct Answer is Right**
Indomethacin crosses the placenta and can cause constriction of the ductus arteriosus, leading to potential ductal closure and pulmonary hypertension in the fetus. This is because prostaglandins, which are involved in maintaining ductus arteriosus patency, are reduced due to the inhibition of COX by indomethacin. Additionally, indomethacin can also affect fetal kidney function and reduce amniotic fluid volume.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the mechanism by which indomethacin affects the fetus.
**Option B:** This option is incorrect because it does not accurately describe the impact of indomethacin on fetal development.
**Option C:** This option is incorrect because it does not provide a clear explanation for the effects of indomethacin on the fetus.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that NSAIDs like indomethacin can have significant effects on fetal development, particularly during the third trimester. This is why they are typically avoided in pregnant women, unless absolutely necessary and under close medical supervision.

**Correct Answer:** D. Indomethacin can cause constriction of the ductus arteriosus, leading to potential ductal closure and pulmonary hypertension in the fetus.