A nurse in the labor and delivery unit is reviewing medications for a group of clients. Which of the following medications places the fetus at risk for teratogenic effects?

A. Levothyroxine for hypothyroidism: Levothyroxine is a thyroid hormone replacement that is considered safe in pregnancy. Proper management of maternal hypothyroidism is essential for fetal neurodevelopment, and it does not pose teratogenic risk. B. Phenytoin for seizure disorder: Phenytoin is an antiepileptic drug associated with fetal hydantoin syndrome, which can cause congenital malformations such as cleft lip, cardiac defects, and skeletal abnormalities. It carries a known risk for teratogenic effects, requiring careful monitoring and potential consideration of alternative therapies. C. Magnesium oxide for constipation: Magnesium oxide is generally safe for use during pregnancy for the treatment of constipation. It does not have teratogenic effects and is considered appropriate for maternal use when needed. D. Ferrous sulfate for chronic anemia: Iron supplementation is essential in pregnancy to prevent maternal anemia and support fetal growth. Ferrous sulfate is safe and does not cause congenital malformations, making it an appropriate therapy during pregnancy.