Pregnant driver. Photo is a screen shot from

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A new study finds that the risk of having a car accident increases by 42% for pregnant women who are driving in the first month of their second trimester, as Karen Kaplan writes for the Los Angeles Times. The study, published in the Canadian Medical Association Journal CMAJ, said the increase is compared with the woman’s accident risk when she was driving three years before her pregnancy, Kaplan writes.

By a woman’s third trimester, however, her car accident risk while driving diminishes considerably, to less than before her pregnancy, Kaplan writes. And after the baby is born, accident risk decreases even more, writes Michaeleen Doucleff for the NPR blog “shots.” The decrease after birth is probably because new mothers drive less or have babies aboard when they do, Donald Redelmeier, the emergency room doctor who led the study, told USA Today reporter Kim Painter.

Redelmeier told Doucleff he got the idea for the study because pregnant women never spoke with him about road safety. To do the study, he and his team examined data for more than 500,000 Ontario, Canada, mothers during a five-year period: four years before the baby was born and continuing for a year after the birth, Doucleff writes.

The reason for the increase in accident risk in the second trimester might be because of hormonal changes during pregnancy, Redelmeier said, although the study did not examine the reason. Doucleff quotes Redelmeier as saying, “I was surprised by the magnitude of the effect…. It’s a substantial risk.”

Painter quotes Redelmeier further:

‘A normal pregnancy is associated with fatigue, nausea, insomnia, anxiety and distraction…. All those changes could contribute to driver error.’

According to the study, increased crash risk affects all pregnant women, regardless of their age or socioeconomic status, the gender of their fetus, whether the baby was born prematurely, and other factors, Kaplan writes. There was only one factor that seemed to influence crash rate: city drivers had a higher crash risk than rural ones.

Redelmeier said he and his team are not suggesting that pregnant women should not drive, Painter writes. “And they certainly shouldn’t leave driving to male partners — who, as mostly young men, have worse crash rates than women, pregnant or not,” he added. Rather, pregnant women just need to slow down and follow the rules of the road, he said.

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