Date: June 2020, Version 3

What is it?

Aspirin (ASA, Angettes 75®, Caprin®, Disprin®, Micropirin®, Nu-Seals®, Resprin®) 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   

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.