Obstetrics - Aspirin in Pregnancy

Low dose aspirin (150mg) in pregnancy

You have been given this leaflet because you have been asked to take a low dose of aspirin (150mg) once a day from 12 weeks of pregnancy until 36 weeks.

What is low dose aspirin?

Aspirin is a blood-thinning medication. It is known as an NSAID (a non-steroidal anti-inflammatory drug). Aspirin is used for many reasons, including to treat pain, fever, or inflammation.

How much aspirin and when to take it?

You will usually be given a pack of 75mg tablets. You will need to take TWO of these tablets to achieve your 150mg dose.
However, always check the strength of the preparation you are given by your GP or community pharmacy.

Take 150mg once a day, it is most effective if taken before bed. If you take your aspirin either with or just after food, it will be less likely to upset your stomach.

Why take low dose aspirin in pregnancy?

Taking a low dose of aspirin reduces the risk of:

• Developing hypertension (high blood pressure) and pre- eclampsia (high blood pressure and excessive protein in your urine)

Low dose aspirin may also reduce the risk of:

• Giving birth to your baby prematurely (before 37 weeks)
• Your baby being smaller than expected

Who should take low dose aspirin in pregnancy?

Your midwife or obstetrician (a doctor who specialises in the care of pregnant women) may recommend that you take a low dose of aspirin if:

• You had hypertension during a previous pregnancy
• You have chronic kidney disease, an active auto-immune disease (for example, lupus or antiphospholipid syndrome), Type 1 or 2 diabetes or you have chronic hypertension
• You have previously given birth to a baby who was smaller than expected
• You have had a previous stillbirth (death of baby inside the womb)
• Abnormal biochemicals markers on your combined screening blood test

Other reasons include two or more of any of the following:

• You are aged 40 years or older, or your BMI is 35 or more at your booking appointment
• There is a family history of pre-eclampsia
• This is a multiple pregnancy (for example, twins or triplets)
• First Pregnancy, or 10 years since your last pregnancy

Your obstetrician may advise you to take low dose aspirin for other reasons, which they will discuss with you. 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.

How will you receive the prescription?

Most risk factors will be identified by your midwife at your first booking appointment. The midwife will provide you with your first box of aspirin and at that point, will send a letter to your GP for repeat prescriptions.

Is low dose 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 it (or other NSAIDs), have a bleeding or platelet disorder, if you have an ulcer or bleeding in your stomach or intestines, or 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.

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:

• Wheezing
• Swelling of the lips, face or body
• Rashes
• Severe stomach pains
• Vomiting blood
• Passing blood in your stools

There is no evidence to suggest low dose aspirin causes any increase in vaginal bleeding during pregnancy or at the time of birth. If you have any questions or concerns about taking low dose aspirin please speak to your obstetrician, GP or midwife.
Please read the information leaflet included with your aspirin for more information about the rarer complications.

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.

Further information

If you have any more questions, please ask your midwife or obstetrician.