ACE Inhibitors


The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.


ACE inhibitors have been shown to cause birth defects when taken during pregnancy.

What are ACE inhibitors?

ACE (angiotensin converting enzyme) inhibitors are heart medications used to decrease blood pressure. They also reduce strain on your heart and make it easier for your heart to pump blood. Types of ACE inhibitors that are available include: ramipril (Altace), benazepril (Lotensin), lisinopril (Prinivil or Zestril), enalapril (Vasotec or Epaned), quinapril (Accupril), captopril (Capoten), perindopril (Aceon), trandolapril (Mavik), fosinopril (Monopril), and moexipril (Univasc). These medications are only available by prescription from your doctor.   

What are ACE inhibitors used to treat?

ACE inhibitors are used to treat high blood pressure. They can also be used as part of a treatment plan for heart failure and to help prevent injury to the kidneys in people who have diabetes. Furthermore, ACE inhibitors can reduce the chances of having a heart attack or stroke in people with high blood pressure.

What is high blood pressure?

High blood pressure (also called hypertension) occurs when the force of blood moving through your blood vessels is too high. This can result in injury to your blood vessels and your bodys organs, such as your heart or kidneys. High blood pressure is often called a silent killer because people frequently do not have any noticeable symptoms that would be indicative of the disease. Expecting moms can sometimes develop high blood pressure even if they have never had blood pressure problems before. If you develop high blood pressure during pregnancy, it will most often begin around 20 weeks after conception and go away once you deliver your baby. However, high blood pressure during pregnancy can cause health problems for both you and your baby, including preeclampsia, a potentially life-threatening condition. You can read more about preeclampsia here. For this reason, it is important to always attend your prenatal check-ups with your doctor so that your blood pressure can be monitored for changes.

How do ACE inhibitors work?

ACE inhibitors lower your blood pressure by preventing the formation of a hormone called angiotensin II. Angiotensin II is responsible for increasing your blood pressure by making your blood vessels narrower and causing other chemicals to be released that can further increase your blood pressure. By preventing the production of angiotensin II, ACE inhibitors allow your blood vessels to expand. This decreases your blood pressure, improves blood flow, and relieves extra strain on your heart and kidneys. ACE inhibitors also increase the amount that you urinate and reduce the overall volume of blood in your body.    

If I am taking an ACE inhibitor, can it harm my baby?

ACE inhibitors can harm your baby if you take them during pregnancy. They have been shown to cause birth defects in all trimesters of pregnancy. All ACE inhibitors carry a black box warning, the strictest FDA warning for prescription drugs, because of the potential to cause injury or death to babies when used by expecting moms during the second and third trimesters of pregnancy. Taking ACE inhibitors during pregnancy can also cause many health problems in your baby by lowering the babys blood pressure and interfering with the development of his or her kidneys. The FDA recommends discontinuing ACE inhibitors as soon as pregnancy is detected.

The following are some of the problems that have been found in babies born to mothers who used ACE inhibitors during the second and third trimesters of pregnancy:

  • The baby does not grow to normal weight
  • The bones in the babys skull are smaller than normal, leaving the brain vulnerable to injury
  • The babys kidneys do not fully develop, do not function properly, or fail altogether 
  • Deformed limbs and underdeveloped lungs 
  • Low blood pressure in the baby 
  • Defects in the babys heart 
  • Problems with brain development
  • Death of the baby 

There has also been evidence showing the dangers of ACE inhibitors when taken during the first trimester. The FDA released an alert in 2006 for the potential risk of harm if expecting moms take ACE inhibitors during the first trimester of pregnancy. This alert was in regards to evidence from a study published in the New England Journal of Medicine. This study analyzed outcomes from 209 babies whose mom had taken an ACE inhibitor during the first trimester of pregnancy. These babies were found to have a more than 2 times greater risk for birth defects in the heart, brain, and spinal cord.

Bottom line: ACE inhibitors increase the risk of birth defects and health problems for the baby if they are taken during pregnancy.

If I am taking an ACE inhibitor and become pregnant, what should I do?

If you become pregnant while take an ACE inhibitor, you should contact your doctor immediately. Your doctor will most likely discontinue your medication for the remainder of your pregnancy. You should also immediately contact your doctor if you are taking an ACE inhibitor and have a menstrual cycle that is delayed by more than 2 days. Your doctor may stop treatment with the ACE inhibitor until you have a pregnancy test. Pregnancy tests should be repeated if your period still has not occurred in a few days following the initial test.

If I am taking an ACE inhibitor, can I safely breastfeed my baby?

There is little evidence available on the safety of ACE inhibitors while breastfeeding. Most ACE inhibitors transfer into breast milk in small amounts. It is recommended to avoid ACE inhibitors while breastfeeding unless they are medically necessary. If an ACE inhibitor is needed for treatment, enalapril and captopril have been identified as usually suitable for breastfeeding by the American Academy of Pediatrics. Enalapril and captopril have been shown to have no negative effects on the breastfed baby, however, the amount of safety data available is still very small. In 12 moms who were taking captopril, there was no effect seen in the breastfed baby. There were also no effects seen in 4 breastfed babies whose moms were taking enalapril. Other ACE inhibitors do not have safety data for breastfeeding available. If you need to take an ACE inhibitor while breastfeeding, your pediatrician should consistently monitor your babys blood pressure.  

Bottom line: ACE inhibitors should not be used while breastfeeding unless medically necessary. If you do use an ACE inhibitor while breastfeeding, ensure to have your babys blood pressure monitored by your pediatrician.

If I am taking an ACE inhibitor, will it be more difficult to get pregnant?

No studies have been conducted on the effects of ACE inhibitors on a womans fertility; however, some evidence has shown that ACE inhibitors can actually increase fertility in men. One study found that 17 men with low sperm counts who took lisinopril had increased total sperm count, sperm motility, and a decreased number of abnormal sperm cells. This study was very small and the results would need to be further analyzed before making any conclusions about the effects of ACE inhibitors on fertility in men.

If I am taking an ACE inhibitor, what should I know?

ACE inhibitors should not be used during pregnancy because they can increase the risk of birth defects in your baby. Generally, ACE inhibitors are not recommended in women of child-bearing age. If you are taking an ACE inhibitor, it is important to use reliable contraception. You should contact your doctor if you are taking an ACE inhibitor and are planning to become pregnant. Your doctor will most likely discontinue your medication until af
ter the birth of your baby.

It is recommended to avoid ACE inhibitors while breastfeeding unless they are medically necessary. If an ACE inhibitor is needed, your babys blood pressure should be monitored by your pediatrician.

If I am taking any medication, what should I know?

This report provides a summary of available information about the use of ACE inhibitors during pregnancy and breastfeeding. Content is from the product label unless otherwise indicated.

You may find Pregistry’s expert report about hypertension here.  Additional information can also be found in the links below. 

Resources for ACE inhibitors during pregnancy and breastfeeding:

For more information about ACE inhibitors during and after pregnancy, contact (800-994-9662 [TDD: 888-220-5446]) or check the following links:

WebMD:. ACE Inhibitors and Heart Disease.

American Heart Association: Why High Blood Pressure is a Silent Killer.

March of Dimes: High blood pressure during pregnancy.


Read the whole report
Last Updated: 31-01-2018
General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.