From the Guidelines
Angiotensin Receptor Blockers (ARBs) should be avoided during pregnancy due to significant risks to fetal development and safety. According to the most recent and highest quality study, 1, treatment with ACE inhibitors and ARBs is contraindicated during pregnancy because they may cause fetal renal dysplasia, oligohydramnios, pulmonary hypoplasia, and intrauterine growth restriction. The mechanism behind these adverse effects relates to ARBs' interference with the renin-angiotensin-aldosterone system, which is critical for normal fetal kidney development and function.
Key points to consider:
- ARBs can cause serious fetal harm, including renal failure, oligohydramnios, skull hypoplasia, lung hypoplasia, growth restriction, limb contractures, and even fetal or neonatal death, particularly when used in the second and third trimesters 1.
- Women who become pregnant while taking ARBs should discontinue them immediately and switch to safer antihypertensive alternatives such as methyldopa, labetalol, or certain calcium channel blockers, which have better established safety profiles during pregnancy 1.
- Women of childbearing potential who are prescribed ARBs should use reliable contraception and have a plan to switch medications before conception when pregnancy is desired.
- The American College of Cardiology/American Heart Association task force on clinical practice guidelines recommends transitioning women with hypertension who become pregnant to methyldopa, nifedipine, and/or labetalol during pregnancy, and avoiding ACE inhibitors, ARBs, or direct renin inhibitors 1.
From the Research
Risks of Using Angiotensin Receptor Blockers (ARBs) During Pregnancy
- The use of ARBs during pregnancy is not typically recommended due to their potential fetal toxicity 2, 3, 4, 5, 6.
- Studies have shown that exposure to ARBs in the second and third trimesters of pregnancy can cause fetotoxicity, including oligohydramnios and renal problems 2, 6.
- There is also evidence to suggest that first-trimester exposure to ARBs may be associated with an increased risk of congenital anomalies, although the evidence is conflicting and may be related to maternal factors and diseases that coexist with hypertension in pregnancy 3, 4, 5.
- Women who become pregnant while taking ARBs should be advised to stop taking the medication as soon as possible and switch to a different class of antihypertensive drugs 2, 4, 5.
- Preconception counseling is crucial to discuss the potential risks of ARBs and other medications, and to evaluate the clinical condition and make any necessary changes to the treatment plan 3, 4.
Specific Risks Associated with ARB Use During Pregnancy
- Oligohydramnios (low amniotic fluid levels) 2
- Renal problems, including renal agenesia (absence of one or both kidneys) 2, 6
- Congenital anomalies, including exencephaly (a rare birth defect in which the brain is outside of the skull) 6
- Preeclampsia (a condition characterized by high blood pressure and damage to the liver and kidneys) 2
Management of ARB Use During Pregnancy
- Women who are taking ARBs and become pregnant should be carefully monitored by their healthcare provider 2, 3, 4.
- The medication should be stopped as soon as possible, and alternative antihypertensive medications should be prescribed 2, 4, 5.
- The pregnancy should be allowed to proceed as long as clinically feasible to optimize maternal and infant outcomes 2.