Which antihypertensive agent is contraindicated in pregnancy?

ACE inhibitors are contraindicated in pregnancy due to their association with significant risks to fetal development. During the second and third trimesters, the use of ACE inhibitors can lead to complications such as oligohydramnios (decreased amniotic fluid), fetal kidney damage, and even potentially life-threatening consequences for the fetus. These agents interfere with the renin-angiotensin system, which is crucial for fetal kidney function and the maintenance of uteroplacental blood flow.

In contrast, while beta-blockers, calcium channel blockers, and thiazide diuretics are used cautiously in pregnancy, they do not carry the same level of risk as ACE inhibitors. Some beta-blockers may even be used if necessary, and certain calcium channel blockers have been found to be relatively safe. Thiazide diuretics can also be used with caution for managing mild hypertension during pregnancy, as they are less likely to adversely impact fetal outcomes compared to ACE inhibitors.