Pregnancy and Risk of Serious Car Crash

Professor, Full SGS Member Director, Clinical Epidemiology Unit Sunnybrook Health Sciences Centre G106-2075 Bayview Avenue Toronto, ON
Dr. Donald Redelmeier, MD

Professor, Full SGS Member
Director, Clinical Epidemiology Unit
Sunnybrook Health Sciences Centre
Toronto, ON

MedicalResearch: What are the main findings of the study?

Dr. Redelmeier: We identified every woman in Ontario, Canada, who gave birth to a newborn baby between 2006 and 2011 and then evaluated each driver for the months before, during, and after pregnancy.  This amounted to about half a million women who accounted for almost 8000 serious crashes that sent the driver to hospital.  We found that the second trimester of pregnancy led to a 42% increase in the risk of a serious motor vehicle crash.  The increased risk included diverse populations, distinct obstetrical cases, different crash characteristics. The risk equated to about twice the population norm but was still below male drivers at this age.

MedicalResearch: Were any of the findings unexpected?

Dr. Redelmeier: We anticipated that the risk would increase since pregnancy causes diverse physiologic changes including fatigue, nausea, distraction, and insomnia.  These changes may contribute to driver error and yet road safety is never discussed in prenatal care guidelines.  We were surprised, however, by the magnitude of the increase in risk, amounting to about 75 life threatening crashes each month in Ontario. We were also surprised that the increase in risk was shared by all women rather than confined to a small subgroup of predictable drivers

MedicalResearch: What should clinicians and patients take away from your report?

Dr. Redelmeier: Pregnancy is associated with an increased risk of a serious motor vehicle crash during the second trimester that merits attention for good prenatal care.  Standard advice includes avoiding excessive speed, signaling turns, yielding right-of-way, obeying stop signs, minimizing distractions, and always using a seatbelt. That’s also good advise for other drivers who share the road and do not want to be partially blamed for a crash that involves a pregnant driver.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Dr. Redelmeier: More research is needed to examine the long term outcomes for mother and child involved in a motor vehicle crash. Additional studies are also justified to examine the effectiveness of physician warnings for improving road safety in this setting. More general improvements in engineering, education, and enforcement could also be examined to reduce the baseline risks of road crashes throughout the community.

Pregnancy and the risk of a traffic crash
Donald A. Redelmeier
, Sharon C. May, Deva Thiruchelvam, and Jon F. Barrett

CMAJ cmaj.131650; published ahead of print May 12, 2014, doi:10.1503/cmaj.131650