Possible benefits of using Aspirin during pregnancy
As a blood thinner, Aspirin is used to prevent inappropriate clotting of blood that could cause thromboses, heart attacks, and strokes. [1] The use of Aspirin during pregnancy is controversial and generally discouraged unless specific health conditions in the mother exist, so that the benefits of using a low dose Aspirin regimen outweigh possible risks.
We'll discuss the conditions under which pregnant women should and should not use Aspiron in more detail below.
Studies have shown that low-dose Aspirin — defined as 60 to 100 milligrams (mg) a day — during pregnancy can reduce the risk of having a premature birth in women who have several risk factors for premature births, like having had a premature birth or preterm labor in the past or having diabetes or high blood pressure. [2]
A French study in women taking low dose Aspirin, also often called "Baby Aspirin", during pregnancy to prevent premature birth showed that the children of these women had fewer problems five years after birth than the children of women who had not taken low-dose Aspirin during the pregnancy. [3]
Low dose Aspirin during pregnancy is also often prescribed for women who have risk factors for developing a pregnancy-associated disease that is called preeclampsia and that causes the blood pressure to rise to extreme and unsafe levels and also damages the kidneys.
This condition can advance to a potentially fatal disease for both mother and child, and this complication of preeclampsia is called eclampsia. Risk factors for developing preeclampsia during pregnancy are having had preeclampsia in a prior pregnancy, diabetes, kidney disease, and chronic high blood pressure.
Although scientific studies have shown that some women at risk for preeclampsia can benefit from taking low dose Aspirin during their pregnancy, there is controversy about which women are the best candidates for this therapy, at which stage of pregnancy such women should start taking Aspirin, and how long and how much Aspirin should be taken in this case. [4]
Other health conditions for which low dose Aspirin are prescribed are conditions that come with an increased risk of blood clotting or thrombosis. These blood clotting conditions can appear in a wide variety of pregnant women, and they include women who have lupus and produce a blood clot producing antibody that is called lupus coagulant [5] or women with a related disease called antiphospholipid syndrome. [6]
Possible risk of using Aspirin during pregnancy
Despite the fact that there are studies that show that low dose Aspirin can be beneficial for pregnant women who live with certain medical conditions, the use of Aspirin, in particular at the regular strength, is associated with a considerable risk for both the mother and the baby.
This is the reason why the U.S. Food and Drug Administration (FDA) issued a warning in 1990 that said the following about the use of Aspirin during pregnancy: "It is especially important not to use Aspirin during the last three months of pregnancy, unless specifically directed to do so by a physician because it may cause problems in the unborn child or complications during delivery." [7]
Aspirin is also included on the list of the California Environmental Protection Agency (CAL/EPA) Proposition 65 of developmental toxins (CAL/EPA Proposition 65 List). This listing means that an expert panel of scientists agreed that there is enough evidence to believe that this substance can harm unborn babies. This does not necessarily mean that Aspirin taken at a low dose for a specific health condition during the harms the baby in any case, but there are several mechanisms how Aspirin can cause problems during pregnancy, especially in the last trimester. [7,8]
Aspirin and other non-steroidal anti-inflammatory drugs (or NSAIDs) work by inhibiting the synthesis of a certain family of inflammatory messenger molecules called prostaglandins. Prostaglandins, however, also have other functions in the body. One of the functions of prostaglandins, for example, is the regulation of production of the mucus in the stomach that protects the stomach wall from the acid in the stomach.
This is the reason why taking Aspirin for a long time can cause stomach problems. [9] In unborn babies, a drop in prostaglandin production happens during birth and is the signal to reroute the blood circulation to use the lungs instead of the placenta as the source of oxygen. Taking a regular adult dose of Aspirin during the last trimester of a pregnancy can cause a drop in prostaglandin production in the baby’s body and can thus cause the rerouting of the blood supply prematurely in the uterus. This can be fatal to the baby. [7,8]
There have also been studies that show that taking Aspirin at the time of the conception or in the first weeks of the pregnancy is associated with an increased risk of miscarriages. [10] One particular study found that there was an 80% increased risk of miscarriage when non-steroidal anti-inflammatory drugs or NSAIDs are used during early pregnancy. The study also proved that the association between the use of NSAIDs and miscarriage was stronger:
- if the initial NSAID use was around the time of conception,
- if NSAID use lasted more than a week.
On the other hand, prenatal use of paracetamol (which is one of the rare drugs relatively safe to take during pregnancy) which is pharmacologically different from NSAIDs and Aspirin, was not associated with increased risk of miscarriage regardless of timing and duration of use. [10]
Nevertheless, there have been other studies that did not find this connection between miscarriage and low dose Aspirin, and therefore it is still under debate whether Aspirin can increase the risk of miscarriages. Aspirin has even, in low doses, been prescribed to women with recurrent early miscarriages in a bid to try to prevent pregnancy loss from happening again.
Since Aspirin can inhibit blood clotting and works as a blood thinner, taking Aspirin during pregnancy can increase the risk of bleeding problems during the delivery.
However, taking low dose Aspirin to decrease the risk of premature birth in women with risk factors for premature birth, did not increase the babies risk for bleeding in the brain in a French study. Bleeding in the brain is a condition premature babies often suffer from.
Aspirin can also delay labor. This is one of the reasons why it is used for women with a high risk of premature birth, but this can cause problems in women that are full term.
Aspirin is associated with a condition in children that is called Reye’s syndrome.[11] This disease which causes are not entirely understood can damage many organs of the body, in particular, the brain and the liver. It can be fatal and children and adults under the age of 20 should not take Aspirin because they are at an increased risk of developing Reye’s syndrome. It is not known whether the risk for the baby of developing Reye’s syndrome after birth is increased if the mother has taken Aspirin during the pregnancy, but since Aspirin is passed into the milk taking Aspirin while breastfeeding is strongly discouraged.
A final word
Aspirin may be recommended in low doses during a pregnancy under specific circumstances, but it can be very dangerous to take Aspirin while you are pregnant under others. This is why pregnant women should only ever use Aspirin in pregnancy if their doctor advises it, and after understanding the risks and benefits.
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