Low dose aspirin

Print
Date: May 2025, Version 1.0

Quick read

Low dose aspirin can be used in pregnancy if recommended by your midwife, GP, or specialist.

What is it?

Aspirin (Nu-Seals®) at low doses of 75 to 150 milligrams per day is often used during pregnancy to prevent pre-eclampsia. It is taken from 12 weeks until the end of pregnancy.

Some fertility clinics prescribe low-dose aspirin for women undergoing IVF and for women who have had previous miscarriages to use around the time of conception and (if successful) into early pregnancy.

Low dose aspirin is also used as a ‘blood thinner’ in some people who have had a heart attack or stroke. Low dose aspirin would usually be used throughout pregnancy for this purpose.

Benefits

What are the benefits of using low dose aspirin in pregnancy?

Low dose aspirin can reduce the chance of you developing pre-eclampsia if you have risk factors for this illness. This is important as pre-eclampsia can be serious for both you and your baby.

Low dose aspirin is used during fertility treatment and in women with previous miscarriages as some studies suggest that it can increase the chance of getting and staying pregnant. 

Low dose aspirin can prevent further life-threatening heart attacks and strokes in people who are at risk.

Risks

What are the risks of using low dose aspirin in pregnancy?

There is no concern that taking low dose aspirin in pregnancy can harm your baby.

Additionally, if you are taking low dose aspirin for pre-eclampsia, you will usually start around week 12 of pregnancy. Aspirin at this stage of pregnancy cannot affect your baby’s development as the baby is already fully formed.

Alternatives

Are there any alternatives to using low dose aspirin in pregnancy?

Not usually. Low dose aspirin is a safe and effective medicine to reduce the risk of pre-eclampsia as well as heart attacks and strokes. It is therefore usually the best option to keep you and your baby well.

No treatment

What if I prefer not to take medicines during pregnancy?

Your doctor will only prescribe medicines when necessary and will be happy to talk to you about any concerns. It is important to take any medicines prescribed to reduce the risk of pre-eclampsia as well as heart attacks and strokes during pregnancy to prevent life-threatening complications.

Will my baby need extra monitoring?

As part of routine antenatal care, most women will be offered a scan at around 20 weeks of pregnancy to check the baby’s wellbeing. Use of low dose aspirin does not itself cause problems that would require extra scans, although additional growth scans will be offered to women with pre-eclampsia. 

Are there any risks to my baby if the father has used low dose aspirin?

There is no evidence that low dose aspirin can harm the baby through effects on the sperm.

Who can I talk to if I have questions?

If you have any questions about 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 (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.