Aspirin and pregnancy

My midwife has recommended for me to take aspirin, why?

6 things to know about aspirin:

1. The midwife will go through a check list to see if you would benefit from aspirin in pregnancy
2. Aspirin will be given to you as a prescription, but you can buy it cheaply in supermarkets.
3. The dose is 150mg a day (taken as 2 small 75mg tablets) from 8-12 weeks until 36 weeks.
4. It is best to take it at night, after you have eaten your evening meal
5. It reduces the risks of small babies and high blood pressure but does not stop them happening altogether.
6. If you forget a tablet one day, don’t worry – just take the next one at the next day.

Your midwife may have advised that you take aspirin, usually 150mg at night (which is two small 75mg tablets) from around 8-12 weeks until 36 weeks. Not everyone needs to take aspirin – midwives go through a check list to determine who could benefit from it. Aspirin is taken to reduce the risk of some complications developing later in pregnancy. Mainly, aspirin reduces the risk of a disorder called pre-eclampsia, which is high blood pressure. It may also reduce the risks of baby being smaller than it should be, and therefore prevent other complications which develop as a result of the placenta not working properly. 

Who may be recommended to take aspirin

• Those who have had high blood pressure in a previous pregnancy
• Those with a history of high blood pressure
• Those with any type of diabetes
• Those with kidney disease
• Those with systemic lupus erythematosus (SLE) or antiphospholipid syndrome
• Those who have had a previous small baby
• Those who have had a previous stillbirth where this was likely related to a placenta not working well

Furthermore, women who have two or more of the following are also recommended to take aspirin:

• Those in their first pregnancy
• Those whose last pregnancy was 10 or more years ago
• Those who have a body mass index (BMI) at the beginning of pregnancy of 35 or more
• Those who are 40 years old or more
• Those with either a twin or triplet pregnancy
• Those with a family history of pre-eclampsia

In addition, sometimes aspirin is recommended following the results of tests in pregnancy. If for example, when you have a screening test for Down’s syndrome, and it comes back with an abnormal level of certain hormones (a low PAPPA or high inhibin) you will also be recommended to take aspirin. To be of benefit, aspirin needs to be started before 16 weeks. You may still be advised to start it after 16 weeks, but it probably won’t be as effective.

Is aspirin safe?

Aspirin is a very safe medicine– it has been taken by hundreds of thousands of women, and we know that it does not cause problems either for mum or baby. The recommended dose is low, much lower than the doses used as a painkiller for example.  It will usually be given to you as a prescription drug by your midwife, although it can also be bought cheaply over the counter in a pharmacy or supermarket. However, It isn’t licensed so pharmacies won’t sell it to you if you tell them you are pregnant (bewilderingly!).

We know from studies that aspirin seems to have the best effect if it is taken in the evening. The reason for this is unclear, and since it is an easy thing to do, it is recommended that you take aspirin in the evening if you can, preferably with an evening meal.

There are very few women who are unable to tolerate aspirin due to side effects. Very rarely, some women find it makes asthma worse, as it is a type of drug known as a ‘non-steroidal anti-inflammatory drug’ such as ibuprofen. Also, there are a small number of women who find that it gives them gastritis or heart burn type pain. Often this can be managed by making sure that you take the aspirin with a meal or on a full stomach. Try to take it at the same time each day, and if you forget, take it as soon as you remember but do not worry if you forget to take it and miss a day. This is not a disaster, simply take it the next day at the usual time. 

What if I can’t tolerate aspirin?

Unfortunately, there is no alternative to aspirin if you cannot tolerate it. Sometimes it can be tolerated by reducing the dose to 75mg. Whilst this might not be as effective, is probably better than nothing. It is important to realise that whilst aspirin reduces the risk of complications, it does not stop them happening altogether. For example, the risk of a small baby might only be reduced by about 25%. In other words, if aspirin was taken by 100 women to reduce the risk of a small baby, around 75 of them would still have a small baby even if they took the medication. It is unclear how much benefit there is to taking aspirin to reduce the risk of pre-eclampsia. It probably has a greater preventative effect on pre-eclampsia which develops earlier in the pregnancy at before 34 weeks (possibly there is a 50% reduction in risk), and less effect on high blood pressure developing nearer the end of pregnancy.