Healthy pregnancy hub

ACE Inhibitors

Last Update: 07 May 2026

Medication
Welcome to our fact sheet on ACE Inhibitors during pregnancy and lactation. This information is based on available published literature. It should not take the place of medical care and advice from your healthcare provider.

The HEALTHY PREGNANCY HUB team is collaborating with MotherToBaby to share information on this topic. The original version is available here (February 2026).

Serene, our chatbot, can also answer your questions about medications during pregnancy.

Please note that this fact sheet is based on United States information and has been adapted for Canada, with a review by our Canadian experts. Minor differences may exist between the two countries. Always consult your healthcare professional for information tailored to your situation.

1. What is an ACE inhibitor?

ACE inhibitor stands for: angiotensin-converting-enzyme (ACE) inhibitor. ACE inhibitors is the name used to describe a group of medications used to treat high blood pressure. ACE inhibitors have also been used for treating some problems with the heart and kidneys. 

ACE inhibitors are sold under many names, such as: benazepril (Lotensin®), captopril (Capoten®), cilazapril (Inhibace®), enalapril (Vasotec ®, Epaned®), fosinopril (Monopril®), lisinopril (Listril®, Lopril®, Novatec®, Prinivil®, Zestril®), perindopril (Aceon®), quinapril (Accupril®), ramipril (Altace®), and trandolapril (Mavik®). 

It is difficult to study a class of medications. Discuss your specific medication with your healthcare provider to see if there are studies for that particular medication. 

Sometimes when people find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take this medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy. 

2. What does research say about the risks during pregnancy?

I take an ACE inhibitor. Can it make it harder for me to get pregnant?

Not enough studies have been done to see if ACE inhibitors can make it harder to get pregnant. 

Can high blood pressure during my pregnancy cause problems?

Uncontrolled high blood pressure in pregnancy could affect the placenta (organ that develops in pregnancy to help get food and oxygen to the baby). This can then cause problems for the developing baby, such as: slow growth (infant smaller overall), low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth), or preterm delivery (birth before 37 weeks of pregnancy). Uncontrolled high blood pressure in pregnancy can also affect multiple organs like heart, kidneys or the liver in pregnant individual.      

Does taking ACE inhibitors increase the chance of miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. It is not known if ACE inhibitors alone increase the chance for miscarriage.  

Does taking ACE inhibitors in the first trimester increase the chance of birth defects?

Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect.  We look at research studies to try to understand if an exposure, like ACE inhibitors, might increase the chance of birth defects in a pregnancy.   

 The majority of studies have not found birth defects to occur more often in those who took or were prescribed an ACE inhibitor in the first trimester of their pregnancy. However, few recent reviews have reported an increased chance of birth defect with the use of ACE inhibitors. Nonetheless, it is difficult to study medications as a group because even though the ACE inhibitors work in similar ways, there are some differences among the individual medications. When drugs are studied as a group, differences for individual drugs could be missed. Also, problems reported in studies may be related to the high blood pressure or medical condition being treated and might not be due to the medication. 

As a precaution, Canadian recommendations generally suggest stopping ACE inhibitors as soon as a pregnancy is confirmed. If you are taking this type of medication, your healthcare professional may suggest a treatment that is more suitable for pregnancy. 

Does taking ACE inhibitors in the second or third trimester cause other pregnancy related problems?

ACE inhibitors should be avoided during the second and third trimester of pregnancy.

When used after the first trimester, ACE inhibitors can cause low levels of amniotic fluid (fluid that surrounds the baby). Low levels of amniotic fluid can lead to health problems for the developing baby. Some of these problems include poor lung development, poor growth, poor development of the skull bones, birth defects, problems with the development of the kidneys and in the most severe cases, death of the developing baby. 

Talk to your healthcare provider right away if you are pregnant and taking any ACE inhibitor.   

Does taking ACE inhibitors in pregnancy affect future behavior or learning for the child?

Studies have not been done to see if ACE inhibitors, in general, can cause behavior or learning issues for the child. 

What screenings or tests are available to see if my pregnancy has birth defects or other issues?

Prenatal ultrasounds can be used to screen for some birth defects. Ultrasound can also be used to monitor the growth of the pregnancy and the level of amniotic fluid (fluid that surrounds the baby). There are no tests available during a pregnancy that can tell if there has been any effect on behavior or ability to learn. If you took an ACE inhibitor during pregnancy, talk to your healthcare provider about screening options, your healthcare provider can help to arrange any appropriate monitoring.

3. Lactating while taking ACE Inhibitors

It may be possible to breastfeed (or pumpwhile taking an ACE inhibitordepending on the specific medication. Contact your healthcare provider to learn more about your specific mediation(s). Be sure to talk to your healthcare provider about all your breast/chest feeding questions. 

4. What about fathers and sperm donors?

If a male takes ACE Inhibitors, could it affect fertility or increase the chance of birth defects?

There is no evidence to suggest that a male’s use of an ACE inhibitor causes infertility (ability to get a person pregnant) or birth defects. In general, exposures that fathers or sperm donors have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures here.

Key points

  • ACE inhibitors are a group of medications used to treat high blood pressure (hypertension) and certain heart and kidney conditions. 
  • Most studies have not found an increased risk of congenital malformations in people who were prescribed an ACE inhibitor early in pregnancy. 
  • There is not enough research to determine whether these medications affect fertility, the risk of miscarriage, or the baby’s brain development. 
  • As a precaution, Canadian guidelines recommend avoiding the use of ACE inhibitors during pregnancy; another treatment may be offered if needed. 
  • Depending on the specific medication taken, it may be possible to breastfeed (or express milk) while taking an ACE inhibitor. 
  • Always talk with your healthcare provider before starting, stopping, or changing any medication during pregnancy or breastfeeding.

References

Please click here for references. 

Additional references 

  1. Fu J, Tomlinson G, Feig DS. Increased risk of major congenital malformations in early pregnancy use of angiotensinconverting-enzyme inhibitors and angiotensin-receptor-blockersa meta-analysisDiabetes Metab Res Rev. 2021 Nov;37(8):e3453. doi: 10.1002/dmrr.3453. Epub 2021 Apr 13. PMID: 33779043. 
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Disclaimer

HEALTHY PREGNANCY HUB provides a source of information validated by health professionals; however, this information is provided for informational purposes only and should not replace professional advice. Medical standards and practices evolve as new data becomes available, so it is imperative to consult your doctor or a qualified health professional for any questions or concerns regarding your health without delay or omission. It is the responsibility of your treating physician or any other health professional, based on their independent experience and knowledge of the patient, to determine the best way to evaluate and treat you.

HEALTHY PREGNANCY HUB does not specifically recommend or endorse any test, practitioner, treatment, product, or opinion mentioned on our platform. HEALTHY PREGNANCY HUB also does not replace the individual patient assessment based on the examination by the healthcare provider of each patient and the consideration of laboratory data and other patient-specific factors.

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While consulting symptoms or other medical information on our platform may guide your discussions with your healthcare professional, this information should not be used to make a medical diagnosis or determine treatment. Before making changes to your supplement or medication regimen, please discuss with your medical team or contact 811 (Canada) to ensure the relevance of these changes to your individual situation.

Credits
MotherToBaby
Organization of Teratology Information Specialists (OTIS)
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Émy Roberge
Centre hospitalier universitaire Sainte-Justine
Sherif Eltonsy
University of Manitoba
Vanina Tchuente
Centre hospitalier universitaire Sainte-Justine

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