Female vets over-exposed to the anaesthetics, X-rays and pesticides they use could be raising their chances of miscarriage, research suggests. The Australian study, in Occupational and Environmental Medicine, found regular exposure to workplace hazards was linked to a doubling of risk.

The vast majority of UK vets are female, but a specialist said health and safety rules were now very tight.

Smaller practices often avoided risky anaesthetic gases altogether, he said.

NHS and veterinary hospitals tend to have so-called "scavenging" equipment designed to suck waste gases such as nitrous oxide away from staff areas.

However, this is impractical for many smaller practices, and there have been concerns about the short term and long-term effects of these gases on staff.

One of the well-known risks of breathing nitrous oxide is an increase in the number of miscarriages, and the study carried out by the University of Western Australia further highlighted the problem.

Researchers quizzed 2,800 vets about their known exposure to anaesthetic gases, X-rays and pesticides.

They found that the risk of miscarriage - the loss of a baby before the 24-week mark in pregnancy - rose by approximately 250% among those who were exposed to "unscavenged" gases for at least an hour a week.

Vets who carried out more than five X-rays a week had an 82% increased risk, while those who reported using pesticides had an 88% increased risk.

Safety equipment

Lead researcher Dr Adeleh Shirangi, who now works at Imperial College London, said: "Prior to our study, there had been very little research looking at female vets' exposures to occupational hazards and how this affects their health.

"We found that many of the vets surveyed either didn't have the safety equipment in their practices, or they had the equipment but weren't using it correctly.

"We hope that our research will make vets aware of the need to fully protect themselves whilst they are working, especially if they planning to have a baby."

Mark Senior, a lecturer in veterinary anaesthesia at the University of Liverpool, said that regulations governing exposure had become significantly tighter in recent years in the UK, with requirements to measure regularly levels of gases in operating theatres.

"However, it is still an issue for practices, particularly as it is arguable that there will be high levels of gases in other areas, for example the recovery room."

He said that many small practices, which could not afford to install gas scavenging equipment, had stopped using nitrous oxide altogether.

Regulations had also been strengthened in exposure to X-rays he said, with all staff involved having to wearing radiation measuring badges.

"The majority of vets in this country are women, and these risks are taken very seriously indeed."