(Date: June 2020. Version: 3)

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 Public Health England 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 is it?

Aspirin (ASA, Angettes 75®, Caprin®, Disprin®, Micropirin®, Nu-Seals®, Resprin®) 
Aspirin is a ‘non-steroidal anti-inflammatory drug’ (NSAID).

Low-dose aspirin (75 to 150 milligrams once per day) is often used as a ‘blood thinner’ to help prevent heart attacks and strokes. During pregnancy it is used to prevent a condition called pre-eclampsia. It is taken from 12 weeks onwards until the end of pregnancy.

Low-dose aspirin is sometimes prescribed by fertility centres for women undergoing fertility treatment (IVF), and in women who have had several miscarriages in a row.

Standard dose aspirin (up to 4 grams per day) is used to treat pain and fever.

Is it safe to take aspirin in pregnancy?

Low dose aspirin
There is no evidence that taking low dose aspirin in pregnancy will harm your baby and for some women it may be recommended (see above). However, you should only take low dose aspirin during pregnancy if advised to do so by your doctor or midwife.

Standard dose aspirin
There is no good evidence that standard dose aspirin causes harm to the baby in early pregnancy. However, the use of standard dose aspirin after 30 weeks of pregnancy is not advised as it can affect the baby. For this reason, paracetamol is recommended to control pain or fever during pregnancy. If paracetamol does not control your pain it is important that you ask your doctor for advice before taking standard dose aspirin or any other anti-inflammatory drug (including ibuprofen).

What if I have already taken aspirin during pregnancy?

If you have taken or are taking any medicines, it is always a good idea to let your doctor know that you are pregnant. Sometimes it is necessary to change a medicine or dosage for pregnancy.

If you have taken standard dose aspirin after 30 weeks’ gestation, particularly for an extended period of time (more than five days in a row), it is important that you let your doctor or midwife know as soon as possible.

What problems can taking standard dose aspirin after 30 weeks of pregnancy cause in my baby?

Standard dose aspirin and other anti-inflammatory drugs like ibuprofen can affect the baby’s circulation and cause a reduction in amniotic fluid levels. Low amniotic fluid can result in problems with the baby’s lungs and limbs.

Wherever possible, use of standard dose aspirin (e.g. to treat pain or fever) during the third trimester of pregnancy should be avoided. Please discuss any concerns that you may have with your doctor.

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

We would not expect any increased risk to your baby if the father took aspirin before or around the time your baby was conceived.

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   

Feedback request 

WE NEED YOUR HELP! Do you have 3 minutes to complete a short, quick and simple 12 question user feedback form about our bumps information leaflets? To have your say on how we can improve our website and the information we provide please visit here.

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.

My bump’s record

Create your own ‘My bump’s record’.

Provide information about your pregnancy to help women in the future.

Login to my bumps

Join my bumps