According to U.S. News, evidence in 2014 indicates that in most circumstances, ibuprofen taken during pregnancy does not increase the risk of miscarriage or birth defect. However, the Guardian cites a study performed in 2011 and published in the Canadian Medical Association Journal which indicates that ibuprofen and drugs like it more than double the risk of miscarriage when taken during the first 20 weeks of pregnancy.
Although earlier studies indicate that ibuprofen may cause complications in pregnant women, newer studies contradict those claims, says U.S. News. Findings published in the Canadian Medical Association Journal in 2014 indicate that there is little or no risk associated with taking ibuprofen and most other over-the-counter nonsteroidal anti-inflammatory drugs, or NSAIDs, during pregnancy. However, some prescription drugs in the same family do slightly increase the risk of miscarriage.
The Guardian article references a 2011 study which found that taking any amount of any NSAID more than doubles the odds of spontaneous abortion. The findings included increased risk among a number of NSAIDs, which "indicates a class effect" of risk associated with this family of drugs. According to this article, the risk that comes with taking any NSAID is very low, but the only pain relief drug that appears to be considered truly safe for pregnant women is acetaminophen.
Miscarriage occurs in approximately 10 percent of all pregnancies and is more common in the earliest weeks of pregnancy, according to U.S. News. In addition to taking certain medications while pregnant, other risk factors, such as smoking and consuming alcohol, increase the likelihood of miscarriage.