Which statement is correct regarding threadworm treatment in pregnancy?

• A. Albendazole is safe in all trimesters
• B. Ivermectin is first line
• C. Metronidazole should be avoided in pregnancy
• D. Pyrantel is contraindicated in pregnancy

Answer: (C)

Treating threadworms in pregnancy requires using a drug that is both effective against the parasite and safe for the fetus. Metronidazole is not active against Enterobius vermicularis, so it wouldn’t solve a pinworm infection. More importantly, when used for any indication in pregnancy, metronidazole is generally avoided, especially in early pregnancy, due to safety concerns and limited evidence of teratogenic risk. Because it does not treat the worm and carries safety cautions in pregnancy, it is not appropriate for threadworm management, making that statement the best fit among the options. In contrast, the drugs that are actually used for pinworms have more favorable safety profiles in pregnancy (with pyrantel pamoate being the preferred option in many guidelines).