Aspirin to Prevent Miscarriage in Early Pregnancy?
Can you decrease the chance for miscarriage by taking a low dose aspirin every day before pregnancy begins?
Miscarriages are a common problem
About half of the women will have a miscarriage at some point during their lives. About 5% will have two miscarriages and 1% will have three or more. Most miscarriages are due to chromosome abnormalities which can't be prevented. But most is not all. Fertility experts like me are always looking for treatments that could reduce the risk for a miscarriage.
Could something as easy as a low-dose aspirin help?
Background about aspirin
Aspirin (also known as acetylsalicylic acid) has been around for a long time. It was first created by a French chemist in 1853. A standard aspirin tablet in the United States contains 325 milligrams of aspirin. Smaller doses of aspirin ranging from 75 milligrams to 81 milligrams are available and commonly referred to as baby aspirin or low dose aspirin. Low dose aspirin has been commonly recommended to reduce the chance for heart attacks in men.
How might low dose aspirin reduce miscarriage risk?
For several years, there has been interest in whether low-dose aspirin could reduce the risk for miscarriage. Why? During pregnancy, the fetus gets all of its oxygen and nutrients from the placenta. The placenta gets oxygen and nutrients from tiny blood vessels in the uterus called spiral arteries. Some miscarriages are thought to occur because of constriction or blockage of the spiral arteries. Aspirin, at low doses, can help dilate blood vessels and prevent blockages by keeping a type of cell called platelets from forming plugs. Theoretically, low-dose aspirin could help reduce miscarriage risk.
Past studies have failed to show a benefit
Past studies, however, have been unable to prove it really works. A 2017 study combined the data from two smaller studies but failed to find a benefit. There were only 250 women studied in this review. Next, there was a bigger study of over a thousand women. This was known as the EAGeR Trial Effects of Aspirin in GEstation and Reproduction. This was a well-designed study.
About half the women were given low-dose aspirin and instructed to take one every day. The other half got a placebo or fake pill with no medication in it. The women didn't know whether they got the real aspirin or the fake. Approximately 12 to 13% of the women in each group miscarried, so there didn't appear to be any benefit to taking low-dose aspirin.
New analysis from the EaGER trial does show a benefit
Recently some researchers went back to the EAGeR study data. They studied those women who had one or two miscarriages before they enrolled in the study. They knew that some of the women who were told to take the low-dose aspirin every day didn't take it. These women were still analyzed as part of the aspirin group even though they didn't take the aspirin. They thought that this could have thrown off the results.
When they compared the miscarriage rate and women who actually took the aspirin to women who didn't, they found something pretty amazing. Out of every 100 women who took low dose aspirin for at least five days each week, there were eight more women who had a positive pregnancy test, six fewer miscarriages and overall 15 more live births than women who did not take aspirin. That's a 15% increase in the live birth rate.
Our bottom line
If you have had one or two previous miscarriages, taking a low low-dose aspirin every day starting before you become pregnant, would seem to improve your odds for having a live birth. It is still uncertain whether women without any previous miscarriages would benefit the same way. But, as long as you don't have any medical reasons that you can't take aspirin this would seem to be an easy inexpensive and low-risk way to improve your odds for having a baby.