(Date: April 2022. Version: 1)

This factsheet has been written for members of the public by the UK Teratology Information Service (UKTIS). UKTIS is a not-for-profit organisation funded by the UK Health Security Agency (UKHSA) on behalf of UK Health Departments. UKTIS has been providing scientific information to health care providers since 1983 on the effects that medicines, recreational drugs and chemicals may have on the developing baby during pregnancy.

What are they?

Diuretics (sometimes called ‘water tablets’) increase urine production and help to get rid of excess fluid. They are used in the treatment of heart failure, high blood pressure and some kidney conditions.

Diuretics commonly used in the UK include amiloride, chlorothiazide, hydrochlorothiazide, furosemide and spironolactone.

What are the benefits of using a diuretic in pregnancy?

Diuretics can be used in pregnancy but are rarely needed. When they are needed, it is to prevent serious complications from the build-up of excess fluid.

What are the risks of using a diuretic in pregnancy?

There is not much information on diuretics in pregnancy because hardly any pregnant women need to take them. However, there are a few issues that need to be considered:

Diuretics may reduce blood flow to the placenta. However, many of the medical conditions that you need diuretics for will also do this. Your baby will be monitored with extra growth scans.

Use of spironolactone specifically can potentially reduce testosterone levels in the baby. There are concerns that use in pregnancy could affect genital development in male babies. This has been shown in animal studies. There is a single human case report of a male baby with malformed genitals following spironolactone exposure, but also several case reports of male babies with normal genitals.

Use of a diuretic in pregnancy will only be recommended if the benefits of treating a potentially serious condition outweigh the possible risks.

Are there any alternatives to taking a diuretic in pregnancy?

Possibly. Women taking a diuretic to treat high blood pressure will usually be offered a different medicine that is known to be safe during pregnancy.

However, pregnant women with heart failure may be advised to continue taking a diuretic, as this can get worse during pregnancy and other drugs are unlikely to be as effective.

Swapping to a diuretic in pregnancy may be advised for women who are taking drugs called ACE-inhibitors and angiotensin receptor blockers, because these are dangerous for the baby if used in later pregnancy.

Women with conditions that affect the kidneys may also be advised to continue taking a diuretic to remain well.

If you are taking a diuretic and planning a pregnancy, speak to your doctor or specialist to make sure that this is right for you. Please do not make any changes to your medication unless your doctor has recommended this.

What if I prefer not to take medicines in pregnancy?

It is important to take any medicines prescribed for high blood pressure, heart problems, or conditions affecting kidney function, as these can be serious for both mother and baby. A doctor will only prescribe medicines when necessary and will be happy to discuss any concerns.

Will I or my baby need extra monitoring?

As part of routine antenatal care, most women will be offered a detailed scan at around 20 weeks of pregnancy to check the baby’s development.

Women with high blood pressure, heart problems, or conditions affecting kidney function will be more closely monitored with additional growth scans during pregnancy to make sure that they remain well throughout and that their baby is growing as expected.

Are there any risks to my baby if the father has taken a diuretic?

We would not expect any increased risk to your baby if the father takes a diuretic.

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 www.uktis.org

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

Our online reporting system allows women with a current or previous pregnancy to create a digitally secure ‘my bumps record’. You will be asked to enter information about your health, whether or not you take any medicines, and your pregnancy outcome. 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 https://www.medicinesinpregnancy.org/Login/ to register.

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General information 

Up to 1 out of every 5 pregnancies ends in a miscarriage, and 1 in 40 babies are born with a birth defect. These are referred to as the background population risks.  They describe the chance of these events happening for any pregnancy before taking factors such as the mother’s health during pregnancy, her lifestyle, medicines she takes and the genetic make up of her and the baby’s father into account.

Medicines use in pregnancy

Most medicines used by the mother will cross the placenta and reach the baby. Sometimes this may have beneficial effects for the baby.  There are, however, some medicines that can harm a baby’s normal development.  How a medicine affects a baby may depend on the stage of pregnancy when the medicine is taken. If you are on regular medication you should discuss these effects with your doctor/health care team before becoming pregnant.

If a new medicine is suggested for you during pregnancy, please ensure the doctor or health care professional treating you is aware of your pregnancy.

When deciding whether or not to use a medicine in pregnancy you need to weigh up how the medicine might improve your and/or your unborn baby’s health against any possible problems that the drug may cause. Our bumps leaflets are written to provide you with a summary of what is known about use of a specific medicine in pregnancy so that you can decide together with your health care provider what is best for you and your baby.   

Every pregnancy is unique. The decision to start, stop, continue or change a prescribed medicine before or during pregnancy should be made in consultation with your health care provider. It is very helpful if you can record all your medication taken in pregnancy in your hand held maternity records.



Disclaimer: This information is not intended to replace the individual care and advice of your health care provider. New information is continually becoming available. Whilst every effort will be made to ensure that this information is accurate and up to date at the time of publication, we cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes following decisions made on the basis of this information. We strongly advise that printouts should NOT be kept for any length of time, or for “future reference” as they can rapidly become out of date.

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