A baby was born with a single-lobed brain and also had neural tube defects. Which drug treatment in the client during her gestation might have caused this condition?

The condition described, specifically the single-lobed brain and neural tube defects, suggests the influence of teratogenic effects that can occur during early pregnancy. Simvastatin is an HMG-CoA reductase inhibitor (statin) used primarily to lower cholesterol. Its use in pregnancy is contraindicated due to its potential teratogenic effects that can disrupt normal fetal development, including the development of the brain and spinal cord. Research has indicated an association between statin exposure during pregnancy and significant congenital anomalies, such as neural tube defects and other structural brain abnormalities.

The other medications listed, while they may have risks associated with their use during pregnancy, do not have the same strong connection to the specific defects mentioned. Nonsteroidal anti-inflammatory drugs like ibuprofen and aspirin are not typically associated with causing major malformations like those described, although they may pose risks during certain stages of pregnancy. Clonazepam, a benzodiazepine, carries a risk of neonatal withdrawal symptoms and potential developmental issues, but it is not particularly linked to the specific brain abnormalities resulting from neural tube defects.

Thus, simvastatin is the drug treatment during gestation that is most likely to have caused the neural tube defects and single-lobed brain in this infant,