The risk of miscarriage more than doubles for women who take anti-inflammatory drugs, some of which are available over-the-counter, during early pregnancy, according to a new study.

Researchers report that any type or dosage of non-aspirin, non-steroidal anti-inflammatory drugs (NSAIDs) can increase the risk of miscarriage up to 2.4 times. These drugs include naproxen, ibuprofen, diclofenac and celecoxib.

Canadian researchers looked at nearly 5000 cases of miscarriage, which included 352 women who took non-aspirin NSAIDs.

Compared to women who did not take NSAIDs during early pregnancy, the women who did take NSAIDs alone or in combination were 2.4 times more likely to spontaneously miscarry.

The highest risk was associated with diclofenac alone and the lowest risk was associated with rofecoxib alone. Dosage did not appear to affect risk.

Prior research has found that taking non-aspirin NSAIDs during pregnancy can increase the risk of major congenital deformations.

“Non-aspirin NSAIDs should be used with caution during pregnancy,” the study researchers recommended.

The study was published in the Canadian Medical Association Journal.