Pregnant women are bombarded with information about what is good or bad for their baby, but surprisingly, advice about wearing seat belts when traveling in cars is not usually included.
The Centers for Disease Control and Prevention (CDC) states that 6,400 adults are injured in car crashes every day and that the risk of serious injury and death is reduced by 50% when wearing a seat belt.
Although the number of people wearing seat belts is increasing, 1 in 7 adults do not wear one on every trip.
And a new study published in the American Journal of Preventive Medicine indicates that motor vehicle crashes can be hazardous for pregnant women, particularly if they are not wearing a seat belt when the accident occurs.
Car crashes are responsible for most injuries requiring hospitalization during pregnancy; however, little is known about the relationship between auto accidents and specific fetal outcomes.
Recording pregnancy outcomes
The study, which is the largest retrospective state-based study of its kind, looked at data for 878,546 pregnant women aged 16-46 years who gave birth to a single infant in the state of North Carolina between 2001 and 2008.
Using vital records and crash reports, investigators were able to study the association among car crashes, vehicle safety features and adverse pregnancy outcomes.
It is known that trauma is a leading cause of maternal and fetal morbidity and mortality. Blunt abdominal trauma is of particular concern to a pregnant woman and her fetus, since it can directly and indirectly harm fetal organs, as well as shared maternal and fetal organ systems.
Investigators focused on four pregnancy outcomes: preterm birth, placental abruption (where the placental lining becomes separated from the uterus), premature rupture of the membranes (which can bring on labor) and stillbirth.
They found that compared with women who were not involved in an auto accident, pregnant drivers had elevated rates of preterm birth, placental abruption, and premature rupture of the membranes after a single crash.
Lead investigator Catherine J. Vladutiu, Postdoctoral Fellow in the Department of Epidemiology at the University of North Carolina's Gillings School of Global Public Health, says:
"This study highlights the importance of crashes during pregnancy and their possible adverse effects on pregnancy outcomes. Clinicians should be aware of these effects and should advise pregnant women about the risk of being in a crash and the long-term consequences that crashes can have on their pregnancies."
Three-fold stillbirth risk in unbelted crashes
While previous studies had only looked at the link between one crash and adverse pregnancy outcomes, this new study also looked at women who had been involved in multiple motor vehicle collisions during their pregnancies.
Following a second or subsequent crash, investigators found pregnant women had more highly elevated rates of preterm birth, placental abruption, premature rupture of the membranes and stillbirth.
The investigators also found that the rates of these unfavorable outcomes increased as the number of crashes increased.
Regardless of the number of crashes, stillbirth rates were elevated following accidents involving unbelted pregnant drivers.
Dr. Vladutiu comments:
"Non-seat belt use and the lack of airbags were associated with elevated rates of selected adverse pregnancy outcomes. Most notably, the stillbirth rate following a crash involving an unbelted pregnant driver was almost three times as high as the stillbirth rate following a crash involving a belted pregnant driver."
While this new study offers greater insight than existing reports, more population-based studies are necessary to increase understanding of the effect of multiple crashes, seat belts and airbags on pregnancy outcomes.
"Given the associations that were observed, a better understanding of the circumstances surrounding crashes during pregnancy is needed to develop effective strategies for prevention," Dr. Vladutiu concludes.