This leaflet has been produced to give you general information about taking aspirin in pregnancy. You have been given this information because your doctor or midwife has advised you to take aspirin. If after reading it you have any concerns or require further explanation, please discuss this with a member of the healthcare team.

Why is aspirin given during pregnancy?

Some pregnant women are at risk of developing pre-eclampsia (a serious condition which usually presents as high blood pressure and protein in the urine) and/or fetal growth restriction (when the baby is smaller than usual due to not growing at a normal rate in the womb).

There is evidence to suggest that this group of women are at reduced risk of developing these conditions if they take a low dose of aspirin during their pregnancy. If you have any of the following conditions taking aspirin from 12 weeks is recommended:

  • History of high blood pressure during your previous pregnancy or current history of high blood pressure
  • Previous pre-eclampsia/eclampsia
  • Chronic kidney disease
  • Autoimmune disease such as systemic lupus erythematosus or antiphospholipid syndrome
  • Diabetes type 1 and 2
  • Chronic hypertension
  • Low Pregnancy Associated Plasma Protein (PAPP-A) screening blood test
  • Previous small baby or previous stillbirth (as per obstetrician discretion)
  • Age 40 years or older
  • If you are a smoker 

If you have more than 1 of the following risk factors you will also be advised to take aspirin during your pregnancy:

  • First pregnancy
  • Pregnancy interval of more than 10 years
  • Family history of pre-eclampsia
  • Multiple pregnancy
  • Body Mass index (BMI) of 35 kg/m2 or more at first visit
  • Previous stillbirth (as per obstetrician discretion)

Your midwife/doctor will indicate which risk factors apply to you

How much aspirin do I need to take?

You will be given a pack of aspirin 75mg dispersible tablets. You will need to take TWO of these tablets once daily to achieve your 150mg dose. You should take your tablets just before bed, as it seems to be more effective when taken at night.

If you take your aspirin either with or just after food, it will be less likely to upset your stomach Please start taking the tablets as soon as you receive the prescription (as this is associated with better outcomes) and continue until 36 weeks. It is important to check the strength of the tablets to ensure you take 150mg daily.

How will I receive the prescription?

Most risk factors will be identified by your midwife at your first booking appointment. The midwife will provide you with a supply of Aspirin. The Aspirin supply will last you until you are 36 weeks pregnant. You should try to start the aspirin between 12 and 16 weeks.

Some risk factors may be identified later in your pregnancy, for example following an ultrasound scan. If this is the case your midwife or doctor will inform you at that time and will notify your GP in the same manner.

Is aspirin safe to take during pregnancy?

Low dose aspirin is not known to be harmful to you or your baby during pregnancy. However, you should only take low dose aspirin if your midwife or obstetrician has advised you to.

Aspirin can affect (and be affected by) other medications, including ‘over the counter’ medicines and herbal remedies. Please discuss any other medications you are taking with your midwife, GP or obstetrician. You should not take aspirin if you are:

  • Allergic to non-steroidal anti-inflammatory drugs (nsaids)
  • Have a bleeding or platelet disorder, if you have an ulcer or bleeding in your stomach or intestines
  • If you are under 16 due to the risk of Reye syndrome
  • If you have experienced severe cardiac failure
  • If you have asthma which can be triggered by ibuprofen or other nsaids.

Taking low dose aspirin does not change any of your choices for pain relief in labour. You can stop taking your low dose aspirin at 36 weeks. There are some rare medical conditions where aspirin would not be recommended. Your doctor will advise you if this applies to you

Aspirin side effects

Mild indigestion is a common side effect and is known to affect 1 in 100 people. If you take your aspirin either with or just after food, it will be less likely to upset your stomach. If you also take indigestion remedies, take them at least two hours before or after you take your aspirin.

As with any medicine, you should seek urgent medical assistance if you experience serious side effects such as:

  • Wheezing,
  • Swelling of the lips, face, or body
  • Rashes
  • Severe stomach pains
  • Vomiting blood
  • Have blood in your poo.

Licensing

Aspirin (like almost all other medication) is not licensed for use in pregnancy. This means that it was originally brought to market to treat other conditions. It does not mean it is not safe to use. When a medication is used ‘off-license’, it is used in the context of a well-reasoned medical recommendation.

Community pharmacies cannot legally sell aspirin as a pharmacy medicine for prevention of pre-eclampsia in pregnancy in England. Aspirin for the prevention of pre-eclampsia and growth restriction must be prescribed.

If you would like more information about taking low dose aspirin in pregnancy, your midwife or obstetrician will be happy to answer your questions and advise you.