Women who take NSAIDs early in pregnancy may up miscarriage risk

Taking non-steroidal anti-inflammatory drugs (NSAIDs) during the early stages of pregnancy may be linked with a higher risk of miscarriage, a study finds.

Canadian and French researchers evaluated 4,705 miscarriage cases up to the 20th week of pregnancy among women age 15 to 45. They were matched with 47,050 controls who did not have a miscarriage at the same point in their pregnancy as corresponding women in the other group.

Among the women who had a spontaneous abortion, 7.5% had previously filled at least one prescription for an NSAID during their pregnancy, compared with 2.6% of women who did not miscarry. After adjusting for a number of factors researchers determined that using a non-steroidal anti-inflammatory drug during pregnancy was linked with a 2.4-fold increase in the risk of miscarriage. The greatest risk was among women who had taken diclofenac, and the lowest among women who had taken rofecoxib alone. The two most common non-aspirin NSAIDs used in the study were naproxen, followed by ibuprofen, but in Quebec, where the study took place, ibuprofen is the only non-aspirin non-steroidal anti-inflammatory drug available over the counter. NSAIDs in general are commonly used during pregnancy.

Some previous studies on the connection between non-steroidal anti-inflammatory drugs and miscarriage or birth defects have shown a link, while others have been inconclusive. A 2003 study in the British Medical Journal found that prenatal use of non-steroidal anti-inflammatory drugs was linked with an 80% greater risk of miscarriage. However, a subsequent BMJ study found the data flawed.

A 2011 study in PLoS One found that although no overall link was found between NSAID use during pregnancy and birth defects, there was a greater risk for septal (heart) defects and exposure to multiple non-steroidal anti-inflammatory drugs in a very small number of cases.

Although the reason for the link is unknown, the authors wrote, “Given that the use of nonaspirin NSAIDs during early pregnancy has been shown to increase the risk of major congenital malformations and that our results suggest a class effect on the risk of clinically detected spontaneous abortion, nonaspirin NSAIDs should be used with caution during pregnancy.”

The study was released Tuesday in the Canadian Medical Assn. Journal.