Which medication class is contraindicated in pregnancy?

ACE inhibitors are contraindicated in pregnancy due to their association with significant fetal risks, particularly during the second and third trimesters. These medications work by inhibiting the renin-angiotensin-aldosterone system, which can lead to decreased blood flow to the placenta and fetal renal issues, resulting in complications such as oligohydramnios, fetal hypotension, and even renal tubular dysgenesis. The use of ACE inhibitors during pregnancy has been linked to adverse outcomes for the developing fetus, making it crucial to avoid these medications in pregnant patients.

While calcium channel blockers and beta blockers may have certain precautions, they are not outright contraindicated and can be used in pregnancy under careful supervision. ARBs, similar to ACE inhibitors, are also contraindicated due to the potential for fetal harm, particularly regarding renal development and function, but the focus of the question identifies ACE inhibitors specifically as a primary concern in pregnancy.