Pregnant women who take painkillers such as ibuprofen are twice as likely to suffer a miscarriage, a study claims.

Women who took painkillers such as ibuprofen just before they conceived until the 20th week of pregnancy were 2.4 times more likely to miscarry, the study stated.

The study published in the Canadian Medical Association Journal involved 47,050 women aged 15 to 45.

Although there are warnings on the labels that they should not be used in pregnancy, as many as one in six expectant mothers still take them.

“We consistently saw that the risk of having a spontaneous abortion was associated with gestational use of diclofenac, naproxen, celecoxib, ibuprofen and rofecoxib alone or in combination,” said Dr Anick Bérard of the University of Montreal.

“Women who were exposed to any type and dosage of non-aspirin NSAID during early pregnancy were more likely to have a spontaneous abortion.”

The study involved a group of painkillers known as Non-Steroidal Anti Inflammatory Drugs or NSAIDS, which include over-the-counter ibuprofen and naproxen. Aspirin is also in this category although it wasn’t included in the study.

Researchers believe taking any number of the drugs can lead to the embryo not being properly implanted in the womb meaning a woman is far more likely to suffer miscarriage, also known as a spontaneous abortion.

Around one in eight pregnancies end in miscarriage and the majority happen in the first 12 weeks.

But doctors pointed out the risks of a woman suffering a miscarriage due to painkillers were very small.  The study did not take into account other possible causes such as smoking and obesity.