Amlodipine During Pregnancy: Safety and Evidence

What does the evidence say about amlodipine during pregnancy?

1. Amlodipine is a calcium channel blocker used for high blood pressure. Research on calcium channel blockers as a group does not suggest an increased chance of birth defects, and a comparative study found no difference in c-section rates, preterm delivery, placental abruption, or growth restriction between amlodipine and nifedipine. 1
2. A large claims-database study examining first-trimester exposure to antihypertensives, including amlodipine, found no increased risk of major congenital malformations. Uncontrolled high blood pressure during pregnancy, on the other hand, has been associated with growth restriction and a higher chance of preterm delivery. 2
3. Reviewing multiple population studies of calcium channel blockers as a class, including a US study (relative risk 0.96) and a Hungarian case-control study of 22,865 infants with abnormalities, found no significant increase in birth defect risk from earlier-pregnancy use. Third-trimester exposure specifically was linked in one analysis to a higher chance of neonatal seizures, jaundice, and blood disorders (relative risk 3.6). 3
4. In a study measuring amlodipine in breast milk, the median concentration was 11.5 mcg/L, and the relative infant dose averaged just 1.7 to 3.3 percent of the weight-adjusted maternal dose. In newborn blood samples, amlodipine was undetectable, and no adverse effects have been reported in breastfed infants. 4
5. Colostrum samples tested for amlodipine came back undetectable in every sample measured, and needing amlodipine is not considered a reason to stop breastfeeding. 4

Is amlodipine safe in each trimester?

• First trimester. If you're already taking amlodipine for chronic high blood pressure, current data on first-trimester exposure, including a large claims-database study, hasn't shown an increased risk of major birth defects. Keeping your blood pressure controlled matters too, since uncontrolled hypertension is linked to growth restriction and preterm delivery on its own.
• Second trimester. Blood pressure management often continues through the second trimester with routine monitoring. Amlodipine and nifedipine performed similarly in a comparative study looking at c-section rates, preterm delivery, and growth restriction.
• Third trimester. This is where the evidence carries one specific nuance: exposure to calcium channel blockers as a class in the third trimester has been linked in one analysis to a higher chance of neonatal seizures, jaundice, and blood disorders. Bring this up with your delivery team so they know what to watch for in your baby.