"Pregnant women often ask me about the safety of air travel , diving with jacuzzis , however many do not believe in accidents , which are the biggest threat during pregnancy ," says the author the study, Dr. Donald Redelmeier , a physician at the University of Toronto and a researcher at the Institute for Clinical Evaluative Sciences (ICES ) .

In the study, researchers have examined more than 500,000 pregnant women in Ontario before, during and after pregnancy. Each woman was followed for five years, including four years before and one year after delivery.

The researchers looked at whether the typical conditions of pregnancy - nausea , fatigue , insomnia and distraction - contributed to making mistakes while driving and therefore a greater risk of accidents.

During the period prior to pregnancy, the study participants were involved in 6,922 accidents ( an average of 177 per month ) . By contrast , women who led during second trimester of pregnancy were involved in 727 accidents ( with an average of 252 per month) , representing an increase of 42 percent in risk.

The researchers saw similar increases in accidents in which women were pedestrians or passengers, nor was there an increase in the number of falls .

The study appears in the May 12 issue of the Canadian Medical Association Journal, under the title of " Pregnancy and the risk of a traffic crash ."

The reason for the link is unclear , but may be because during the second quarter , women develop a false sense of security that is often exacerbated by insomnia , back pain and more hectic life general.

These findings , according Redelmeier , stress the need for pregnant women to consider safe driving as part of their prenatal care . " No need to hire a driver or someone driving by them. You just have to be a little more alert when driving. Use seatbelts , reduce speed and minimize distractions . Though this is also good advice for any driver . "

Picture Tom Adriaenssen [CC-BY-3.0-2.5-2.0-1.0], via Wikimedia Commons