Pregnancy is associated with a significant risk of a serious car crash requiring emergency medical care during the second trimester（中期妊娠）, according to a research paper published in CMAJ (Canadian Medical Association Journal). Traffic mishaps（灾祸） place mother and baby at risk of fetal death, chronic disability and complicated emergency medical care.

A study of 507 262 pregnant women looked at whether common features of pregnancy such as nausea（恶心）, fatigue, insomnia, and distraction could contribute to human error and the risk of a traffic crash requiring emergency medical care. During the 3 years before pregnancy, the women had 6922 crashes (177 per month). During the second trimester, the women, as drivers, had 757 crashes (252 per month). The elevated risk during the middle of pregnancy equalled a 42% increase in serious traffic crashes from baseline.

"Pregnant women often worry about air flights, scuba diving, hot tubs and other topics in maternal health, yet individuals may overlook traffic crashes despite their greater health risks," states lead author Dr. Donald Redelmeier, a researcher with the Institute for Clinical Evaluative Sciences (ICES) and a physician at the Department of Medicine, University of Toronto, Toronto, Ontario.

Statistically, about 1 in 50 pregnant women will be involved in a motor vehicle crash at some point during pregnancy.

"The increase was almost fully explained by multiple-vehicle crashes in which the woman had been driving a car (not a truck or other miscellaneous vehicle) and had a high triage urgency," writes Dr. Jon Barrett, chief of maternal fetal medicine at Sunnybrook Health Sciences Centre, Toronto, with coauthors. "Almost all traffic crashes could be prevented by a small change in driver behaviour. The absolute risks among pregnant women, however, are still lower than among men of this age," emphasizes Dr. Redelmeier.

The researchers did not see similar increases among women who were pedestrians（行人） or passengers nor increases in the number of falls or risky behaviours.

Dr. Redelmeier stresses, "These findings are not a reason to decide not to have children or a reason to stop driving; instead, the findings primarily emphasize the need to drive more carefully." Standard advice includes avoiding excessive speed, signalling turns, yielding right of way, obeying stop signs, minimizing distractions and always using a seatbelt when pregnant.

"Even a minor motor vehicle crash during pregnancy could lead to irreparable consequences for mother and child," states Dr. Redelmeier. "These findings underscore the importance of prevention and indicate that good prenatal care includes safe driving."