Which antihypertensive is contraindicated during pregnancy due to its teratogenic effects?

The correct answer is that ACE inhibitors are contraindicated during pregnancy due to their teratogenic effects. During pregnancy, especially in the first trimester, the use of ACE inhibitors can lead to serious fetal complications. These complications can include cardiovascular malformations, renal dysfunction, and even fetal demise if the drug is continued during the second and third trimesters. The inhibition of the renin-angiotensin-aldosterone system by ACE inhibitors significantly affects fetal development, particularly by disrupting the normal pattern of fetal renal and lung development.

In contrast, other antihypertensive medications like beta-blockers, calcium channel blockers, and diuretics are generally considered safer alternatives for managing hypertension in pregnant patients, although they still require careful monitoring. For instance, while beta-blockers have mixed data regarding safety, especially certain types, they are often used with caution. Calcium channel blockers are typically seen as low-risk and are often prescribed when necessary. Diuretics can be used but are generally approached with caution, considering the potential for reduced plasma volume.

Overall, the significant teratogenic risks associated with ACE inhibitors clearly establish them as contraindicated during pregnancy, making this the correct choice.