Step 1: Understanding teratogenicity.
Teratogenicity refers to the ability of a substance to cause birth defects in a developing fetus. Chloramphenicol is known to be teratogenic and should be avoided during pregnancy.
Step 2: Analyzing the options.
(1) Chloramphenicol: Correct — Chloramphenicol is known to be teratogenic and can cause fetal harm.
(2) Aspirin: Incorrect, while aspirin can cause some risks during pregnancy, it is not typically teratogenic.
(3) Paracetamol: Incorrect, Paracetamol is generally considered safe for use during pregnancy and is not teratogenic.
(4) Cetirizine: Incorrect, Cetirizine is an antihistamine that is not associated with teratogenic effects.
Step 3: Conclusion.
The correct answer is (1) Chloramphenicol.