Woman are more likely to be injured in a car crash when expecting. (Image credit: Getty Images)

By Bharat Kumar, MD

As if pregnant women needed something else to worry about. A new study suggests they face a higher risk of being in a serious car crash.

Canadian researchers reviewed the medical records of half a million women who gave birth between 2006 and 2011 and found they were 42 percent more likely to be in a traffic accident when they were expecting.

Donald Redelmeier, a senior scientist at the Institute for Clinical Evaluative Sciences in Toronto and lead author of the study published today in the Canadian Medical Association Journal, said he became concerned about driving safety after talking to pregnant patients.

"They often ask me about flying on planes, sitting in hot tubs and scuba diving," Redelmeier told ABC News. "But never have I been asked about traffic accidents, despite the possible threat."

Redelmeier said he decided to investigate the risk when he realized no one had before.

"Because pregnancy isn't an illness and road crash isn't a medical disease, it simply wasn't in any of the textbooks," he said.

The study found that nearly one out of fifty women will be involved in a car crash while pregnant - a figure on par with the risk of preeclampsia, a condition marked by high blood pressure during pregnancy.

It is not entirely clear why pregnant women are at increased risk, but the study suggests that a mix of the stress and other pregnancy symptoms like nausea, fatigue, back pain and sleeplessness might make it harder to concentrate on the road.

Dr. Jennifer Ashton, ABC News' senior medical contributor and a practicing OB/GYN, said the results of the study are surprising.

"In more than 10 years and after having delivered well over 1,000 babies, I have never had a patient involved in a motor vehicle accident while pregnant," she said.

Nevertheless, Ashton said she would "definitely counsel them that this may be an issue and try to encourage risk reduction techniques… and reminding them about seat belt use even when the uterus is very enlarged."

Doctor's Take

While the results of this study are interesting, it's important not to stigmatize pregnant women based on these findings. In other words: being pregnant while driving is a far cry from driving under the influence or texting at the wheel.

What should pregnant take away from the findings? Redelmeier's advice is to get back to the basics of road safety, "the kind of stuff they taught you when you were 16 in driver's ed: full stop at red lights, signal turns, avoid driving when feeling tired, hanging up cellular phones and minimizing distractions."

"The everyday sloppiness you can get away with, you may not be able to when you're off-balance during pregnancy," he said.