A class of drug called "benzodiazepines" -- which is used in the treatment of anxiety, depression and insomnia -- could be linked to higher odds for miscarriage if taken during pregnancy, a new study has found.

Benzodiazepines, generally known as benzos, are a class of sedative medications. Xanax, Valium, Ativan, and Klonopin are some of the most well-known drugs, reports Daily Mail.

In the study, published in the journal JAMA Psychiatry, researchers from Taiwan looked at miscarriages among women exposed to benzos before getting pregnant only, during pregnancy and during both time periods.

They studied over three million pregnancies in two million women and found that 4.4 per cent -- or 136,130 -- resulted in miscarriages.

They analysed the medical history of all the women studied and found those prescribed benzos were, on average, 70 per cent more likely to miscarry compared to those who didn't take the pills, the study noted.

The researchers also mentioned that this higher risk persisted even when other confounding factors such as the woman's age and health were taken into account.

The risk of miscarriage was increased by 67 per cent with long-acting benzos like Valium, compared to 66 per cent with short-acting benzos like Versed.

Alprazolam, the generic version of Xanax, showed the lowest risk association, at 39 per cent, according to the study.

As per researchers, benzos, when used during pregnancy, can cross the barrier between the mother and the placenta, exposing a fetus to the drugs.

Researchers theorised that because benzodiazepines have a role in cell development and growth, benzodiazepine exposure could cause fetal developmental defects, which could lead to miscarriage.

While the study found a relationship between benzos and miscarriages, researchers were unable to establish a direct link.

The researchers did account for underlying diseases that could have caused miscarriage, but they did not assess the impact of a combination of factors, such as smoking and anxiety.