## **Core Concept**
The question tests knowledge on the safety profile of antimalarial drugs during pregnancy, focusing on the risk-benefit analysis of various antimalarials in pregnant women. Pregnancy alters the pharmacokinetics of many drugs and increases the risk of certain adverse effects. The safety of antimalarial drugs during pregnancy is crucial due to the potential risks to both the mother and the fetus.

## **Why the Correct Answer is Right**
Chloroquine has been used for decades in the treatment and prophylaxis of malaria and is considered safe in pregnancy for the treatment of uncomplicated malaria caused by *Plasmodium vivax*, *P. ovale*, *P. malariae*, and some strains of *P. falciparum* that are still susceptible. Its safety profile in pregnancy, especially when used for malaria prophylaxis or treatment, makes it a preferred option. However, resistance patterns, particularly in areas with *P. falciparum*, must be considered.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Mefloquine is used for prophylaxis but can have neuropsychiatric side effects and is generally avoided in the first trimester if possible.
- **Option B:** Doxycycline is contraindicated in pregnancy due to the risk of inhibiting bone growth and causing tooth discoloration in the fetus.
- **Option D:** Primaquine is contraindicated in pregnancy, especially in the first trimester, due to the risk of hemolysis in the fetus, particularly in those with glucose-6-phosphate dehydrogenase (G6PD) deficiency.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that while chloroquine is considered relatively safe, areas with chloroquine-resistant *P. falciparum* require alternative treatments. Pregnant women with malaria should be treated promptly and effectively to reduce maternal and fetal morbidity and mortality.

## **Correct Answer:** C. Chloroquine.