Angiotensin converting enzyme inhibitors (ACE-I)

Date: March 2024, Version 4

What are they?

ACE inhibitors (ACE-I) are used to treat high blood pressure, heart failure, and kidney disease. Specific ACE-I include captopril [Capoten®, Co-zidocapt®*, Capozide®*], cilazapril [Vascace®], enalapril maleate [Innovace®, Innozide®*], fosinopril sodium, imidapril hydrochloride [Tanatril®],  lisinopril [Zestril®, Carace Plus®*, Zestoretic®*], moexipril hydrochloride [Perdix®], perindopril erbumine, perindopril arginine [Coversyl® Arginine, Coversyl® Arginine Plus*], quinapril [Accupro®, Accuretic®*], ramipril [Tritace®, Triapin®*], trandolapril [Gopten®, Tarka®*]).

Note: products marked in the list above with * combine an ACE-I with another type of medicine.


What are the benefits of using an ACE-I in pregnancy?

ACE-I should not be used in pregnancy. If you are taking an ACE-I and planning a pregnancy you should speak to your GP or specialist to discuss the possibility of switching to a different medicine before pregnancy. 

If you discover that you are pregnant whilst taking an ACE-I, you should contact your doctor as soon as possible so that you can be switched to another medicine.

If you have taken an ACE-I in the second or third trimester of pregnancy it is important to let your doctor or midwife know straight away as your baby will need extra monitoring (see below).


What are the risks of taking an ACE-I in pregnancy?

Taking an ACE-I during the second and third trimesters (specifically from around 20 weeks of pregnancy) can cause a number of problems in the baby:

•    Reduced levels of amniotic fluid around the baby in the womb (oligohydramnios)

•    Damage to the baby’s kidneys which can lead to long-term kidney problems after birth 
•    Underdevelopment of the skull bones

•    Reduced growth in the womb

•    Underdevelopment of the lungs

•    Contracted (stiffened) joints

Additionally, use of an ACE-I in later pregnancy has been linked to an increased chance of stillbirth, preterm delivery, and low infant birth weight.

Women who have taken an ACE-I before realising they are pregnant can feel reassured that ACE-I use in early pregnancy does not seem to be linked to miscarriage. It is clear that the vast majority babies exposed to ACE-I in early pregnancy do not have a malformation. Babies exposed in the womb to ACE-Is in early pregnancy also do not seem to have a higher chance of preterm birth or low birth weight.


What are the alternatives to taking an ACE-I in pregnancy?

There are a number of other medicines that can be used to treat high blood pressure, heart failure and kidney disease in pregnancy. Your specialist will be able to advise on which of these is right for you.

No treatment

What if I prefer not to take any medicines during pregnancy?

The medicine(s) that your doctor has prescribed in place of an ACE-I will have been chosen because they are safer for the baby. It is important to take medicines prescribed for hypertension, heart failure or kidney disease as these conditions carry serious risks for both mother and baby. Your doctor will only prescribe medicines when absolutely necessary and will be happy to talk to you about any concerns.

Will my baby need extra monitoring during pregnancy?

All women are offered a detailed scan at around 20 weeks of pregnancy as part of their routine antenatal care. Women who have used an ACE-I in the first trimester will not require any extra monitoring for birth defects.

Women who continue to take an ACE-I during the second or third trimester will require additional monitoring to assess amniotic fluid levels and their baby’s growth and wellbeing.  

Are there any risks to my baby if the father has taken an ACE-I?

We would not expect any increased risk to your baby if the father takes an ACE-I.

Who can I talk to if I have questions?

If you have any questions regarding the information in this leaflet, please discuss them with your health care provider. They can access more detailed medical and scientific information from

How can I help to improve drug safety information for pregnant women in the future?

Our online reporting system (MyBump Portal) allows women who are currently pregnant to create a secure record of their pregnancy, collected through a series of questionnaires. You will be asked to enter information about your health, whether or not you take any medicines, your pregnancy outcome and your child's development. You can update your details at any time during pregnancy or afterwards. This information will help us better understand how medicines affect the health of pregnant women and their babies. Please visit the MyBump Portal to register.

General information
Sadly, miscarriage and birth defects can occur in any pregnancy.

Miscarriage occurs in about 1 in every 5 pregnancies, and 1 in every 40 babies are born with a birth defect. This is called the ‘background risk’ and happens whether medication is taken or not.

Most medicines cross the placenta and reach the baby. For many medications this is not a problem. However, some medicines can affect a baby’s growth and development.

If you take regular medication and are planning to conceive, you should discuss whether your medicine is safe to continue with your doctor/health care team before becoming pregnant. If you have an unplanned pregnancy while taking a medicine, you should tell your doctor as soon as possible.

If a new medicine is suggested for you during pregnancy, please make sure that the person prescribing it knows that you are pregnant. If you have any concerns about a medicine, you can check with your doctor, midwife or pharmacist.

Our Bumps information leaflets provide information about the effects of medicines in pregnancy so that you can decide, together with your healthcare provider, what is best for you and your baby.