Aspirin® during pregnancy


During pregnancy, headaches and aching limbs are more frequent due to the hormonal changes. As a result, the most commonly used painkiller in Germany is often taken: Aspirin®. Particularly during pregnancy, it is important to ensure that the correct dosage is taken.

The active ingredient acetylsalicylic acid (ASA) contained in Aspirin has a dose-dependent blood-thinning (low dosage) or pain-relieving (high dosage) effect. Particularly at the end of pregnancy and birth, the blood-thinning effect of aspirin could pose risks for the child and the mother. Therefore, the use of Aspirin® should be avoided during the last third of the pregnancy.

Indication during pregnancy

As a matter of principle, the use of medication during pregnancy should be avoided whenever possible. In some cases, the use of herbal products (e.g. for headaches and aching limbs), which usually have a smaller side effect profile, may be advisable instead. A low dosage (100mg) of Aspirin® is used for prophylaxis and when pre-eclampsia is suspected.

During pregnancy, high blood pressure and increased protein excretion occur. At the same time, the placenta, among other things, is less supplied with blood. There is a risk of fetal complications with growth disorders and premature dissolution of the placenta.

Without treatment with Aspirin®, a transition to eclampsia (characterized by maternal seizures, among other things) with a poor prognosis for mother and child is possible. Low-dose therapy with Aspirin® (so-called low-dose treatment) significantly reduces the risk. In addition, low-dose treatment with Aspirin® is also indicated for prevention in the case of repeated spontaneous abortions.

Active substance

The active ingredient of Aspirin® is acetylsalicylic acid (ASS). Depending on the dosage, it has a blood-thinning (low dosage) or pain-relieving effect (high dosage). It develops its effect by inhibiting various enzymes that occur both in the mother’s body and in the baby’s body. These enzymes play a role in the production of prostaglandins, which are involved in the development of pain, blood clotting and the development of labour.

Effect on the baby

After absorption into the mother’s bloodstream, the active substance passes unhindered through the placenta into the child’s blood. The consequences of a blood-thinning effect in the baby’s body are still being investigated in studies. The side effects that can occur when taking aspirin during pregnancy in the baby’s development depend on the dose and the time at which the drug is taken.

Studies have shown that there is no evidence of developmental problems when taking aspirin during the first two thirds of pregnancy. Individual risks (kidney malformations, undescended testicles, increased risk of spontaneous abortions) could not be confirmed in studies. For safety reasons, however, taking aspirin during this period is not recommended.

In the last third of pregnancy, taking Aspirin® can have serious effects on pregnancy and birth. For this reason it is forbidden to take Aspirin® during this period. By inhibiting the synthesis of prostaglandins, the contractions are prolonged.

In the past, this effect was used to treat tocolysis (early onset of labour). In addition, if Aspirin® is taken, an increased blood loss of the mother during birth is to be expected. This is due to the blood-thinning effect of the active ingredient.

At the same time, there is a risk that the child will be undersupplied with blood. In addition, taking Aspirin® can also lead to a narrowing or premature closure of the ductus arteriosus (Botalli). As a consequence, serious blood pressure imbalances in the lung area are to be feared.

Finally, if taken in very high doses, the blood-thinning medication can also lead to an increased incidence of cerebral haemorrhages in children. The Ductus Botalli represents a connection between the pulmonary arteries and the fetal blood circulation in the mother’s abdomen during the development of the child. The absence of breathing during development means that the blood supply to the lungs is bypassed.

Normally, this connection closes a few days after birth. The use of Aspirin® can cause narrowing or premature closure of the duct from the 28th week of pregnancy. As a result, there is a risk of greatly increased blood pressure in the area of the pulmonary circulation. At the same time, the supply of blood to other tissues may be restricted, which impairs development. If therapy with aspirin cannot be discontinued during pregnancy, regular monitoring of the duct with ultrasound and a Doppler device during the last third of the pregnancy is indicated.