## **Core Concept**
The question pertains to the management of tuberculosis (TB) in pregnancy, focusing on the safety of anti-tuberculosis treatment (ATT) drugs during pregnancy. Certain ATT drugs are known to have teratogenic effects or can cause complications in pregnancy.

## **Why the Correct Answer is Right**
The correct answer, **Ethambutol** is not typically the most concerning ATT drug in pregnancy, but **Streptomycin** (an aminoglycoside) is notably avoided due to its potential to cause ototoxicity in the fetus. However, among the commonly used first-line ATT drugs, **Isoniazid (INH)**, **Rifampicin**, and **Ethambutol** are generally considered safer. The concern usually revolves around **Streptomycin**, an aminoglycoside used in some TB treatment regimens, which can cause fetal ototoxicity.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Isoniazid (INH) is generally considered safe in pregnancy, though it requires pyridoxine supplementation to prevent neuropathy.
- **Option B:** Rifampicin is also considered relatively safe, used to treat TB in pregnant women with certain precautions.
- **Option D:** Ethambutol is used cautiously but is not strictly contraindicated.

## **Clinical Pearl / High-Yield Fact**
A critical point to remember is that **Streptomycin** is an ATT drug that should be avoided in pregnancy due to the risk of ototoxicity to the fetus. This is a high-yield fact for exams and clinical practice.

## **Correct Answer:** . Streptomycin