Can Baby Aspirin During Pregnancy Prevent Recurrent Miscarriage?

Some expectant mothers and women who are trying to conceive take meticulous care to avoid taking any over-the-counter painkillers — along with raw cheese, raw fish, and wine — in case something bad happens to the baby (they might be carrying). The belief that using any kind of medication may induce a miscarriage or birth defects isn't that uncommon, and some women ask the question: How much Aspirin can cause a miscarriage?

What Causes Recurrent Miscarriages?

Recurrent miscarriage, or recurrent pregnancy loss, can either be defined as two or three consecutive miscarriages, depending on whom you ask. If defined as three consecutive pregnancy losses, recurrent miscarriage affects around one percent of women who are trying to get pregnant, while that jumps to five percent if defined as two pregnancy losses [1]. 

The most common causes of repeated miscarriage are:

• Chromosomal or genetic abnormalities
• Uterine abnormalities
• Immune-system disorders
• Hormonal problems, including diabetes and thyroid disorders
• Blood-clotting disorders [2]

We'd like to add that stress, commonly cited as a trigger for miscarriage, absolutely doesn't seem to have anything to do with pregnancy loss. Over 50 percent of women who have suffered repeated miscarriages won't know why — even once tests are conducted [2]. It's those women who do gain insights into the causes of their recurrent pregnancy loss who may have the chance to prevent it from happening again. It's women with certain blood-clotting disorders who may benefit from taking baby Aspirin during pregnancy. 

Thrombophilia As A Cause Of Recurrent Miscarriage

The blood is normally, to put it rather simply, meant to maintain a perfect balance — it's meant to clot so it can stop you from bleeding out when you're injured, but not so much that it forms blood clots inside your body, putting your life at risk. If you suffer from thrombophilia, you are more likely to form blood clots. These can increase your risk of heart attacks, strokes, deep vein thrombosis, and a pulmonary embolism, as well as miscarriage. This is because a blood clot may block the placenta's blood vessels. These blood-clotting disorders come in rather a few different types, with different causes. One example is the auto-immune disease antiphospholipid syndrome. Recurrent miscarriages or the inability to conceive is, in fact, one reason for which doctors will suggest you be tested for a thrombophilia. [3]

Since an approximate 15 percent of women who have had repeated miscarriages have antiphospholipid antibodies, it is not as rare a cause of miscarriage as you may have guessed [4]. 

Recurrent Miscarriages: Where Does The Baby Aspirin Come In?

Several studies looked at the possibility that low-dose Aspirin — 75 mg daily — could prevent further miscarriages in women who tested positive for antiphospholipid antibodies, lupus anticoagulant or anticardiolipin antibodies. Women taking this low dose of Aspirin during their pregnancies had a high live birth rate, leading researchers to conclude that: "Aspirin may improve pregnancy outcome in women with antiphospholipid antibodies by irreversibly blocking the action of cyclo-oxygenase in platelets, thereby inhibiting platelet thromboxane synthesis and preventing thrombosis of the placental vasculature." [5]

A study that evaluated the merits of offering low-dose Aspirin to pregnant women without antiphospholipid antibodies led to the conclusion that this treatment does not lead to improved pregnancy outcomes in this group [6]. Yet another study, fascinatingly, found that women who had repeated early miscarriages, defined as those taking place at 13 weeks gestation or less, did not improve pregnancy outcomes by taking baby Aspirin during pregnancy. Those with late miscarriages, however, had improved birth rates compared to their counterparts who took a placebo. [7]

Several studies were also conducted to find out if combining baby Aspirin with heparin, another medication used to prevent the formation of blood clots [8] would help women with and without thrombophilia prevent having a miscarriage. The jury's out on this one — authors of a paper analyzing previous studies in this department simply concluded that the benefit of taking baby Aspirin and heparin during pregnancy hasn't been proven in women who have suffered recurrent miscarriage. [9]

Should I Take Baby Aspirin During Pregnancy To Prevent Miscarriage?

You have several things to consider, here. Not a single study has shown that taking low-dose Aspirin during pregnancy increases your risk of having a miscarriage, though you should certainly consult your healthcare provider before using higher doses. Several studies have questioned the benefit of using either Aspirin or Aspirin in combination with heparin for women seeking to prevent miscarriage, but in light of the previous fact — does that matter? If there is any chance at all that taking baby Aspirin during pregnancy could help you get pregnant and stay pregnant, shouldn't you try? This is, in short, a matter for you and your treating physician to talk about.