Pregnant driver-associated motor vehicle crashes in North Carolina, 2001–2008
Introduction
In the United States, motor vehicle crashes are the leading cause of maternal injury-related death during pregnancy (Rochat et al., 1988). A pregnant occupant crash rate of 13 per 1000 person-years was estimated from a probability sample of pregnant occupant crashes in the U.S., while a rate of 26 per 1000 person-years was estimated for non-pregnant women during the same period (Weiss and Strotmeyer, 2002). However, the pregnant occupant crash rate is likely an underestimate due to difficulties in capturing cases. Statewide crash surveillance is lacking and administrative databases are limited, as crash records lack information on pregnancy status and vital records lack data on crash history.
A few studies have addressed these limitations by using linked data sources (i.e., police crash reports and vital records) to estimate state-level pregnancy crash risks (Weiss et al., 2011, Schiff et al., 2010, Hyde et al., 2003). These risks (ranging from 1.0% to 2.8%) are better estimates of crashes during pregnancy, but the denominators do not account for variable time spent driving a motor vehicle during pregnancy. A recent study suggested that these estimates may be on the “lower end of the risk spectrum” since they are from states that have older maternal ages at birth and lower overall severe crash risks in older women (i.e., Washington State, Pennsylvania) or younger maternal ages and lower severe crash risks among younger women (i.e., Utah) (Weiss et al., 2011). The pregnancy-associated crash risks in states, such as North Carolina (NC), that have higher severe crash risks among women of reproductive age are unknown (Weiss et al., 2011).
Pregnant women are an understudied population in motor vehicle safety research, thus little is known about the characteristics of pregnant drivers in crashes and the circumstances surrounding these crash events. This information is important for informing the development of crash prevention strategies. Our objectives were to use linked data sources in NC to estimate the overall risk of being a pregnant driver in a crash, to estimate crash risks by selected maternal characteristics, and to describe the characteristics of pregnant driver-associated crashes among pregnant women, aged 16–46 years, with singleton pregnancies.
Section snippets
Study population
This study included a cohort of 878,546 pregnant NC residents, 16–46 years, who reached the 20th week of pregnancy and delivered a singleton infant in NC between January 1, 2001 and December 31, 2008 (Fig. 1). These women were identified from live birth and fetal death records from the NC State Center for Health Statistics (n = 993,274). We removed records for pregnant women aged less than 16 years at the time of delivery (n = 7075) because driver crashes in this pre-licensure age group are
Study population
A total of 878,546 pregnant women met the eligibility criteria in 2001–2008. High proportions of these women were 25–34 years old, non-Hispanic white, educated at least through high school, married, began prenatal care before the 20th week of pregnancy, did not use tobacco or alcohol during pregnancy, and had at least one prior live birth (Table 1). The mean number of weeks of pregnancy completed by women in this cohort was 38.7 weeks (standard deviation = 2.7); the median was 39.0 weeks.
There
Discussion
Previous state-level linkage studies have estimated pregnancy crash risks that ranged from 1.0% among pregnant front seat occupants in Washington State (Schiff et al., 2010) to 2.8% among pregnant drivers in Utah (Hyde et al., 2003). A recent study in Pennsylvania (Weiss et al., 2011) reported a crash risk of 1.1% among pregnant drivers. However, these studies counted crashes that occurred at any detectable time during pregnancy, despite the undercount of pregnancies at risk early in pregnancy,
Conclusion
As one of only four U.S. states that have used linked records to quantify the risk of being a pregnant driver in a crash, NC has a relatively high pregnant driver crash risk. This risk may be even higher in other states, particularly those with crash risks among reproductive-aged women that are higher than in NC (e.g., Mississippi, Montana, Wyoming). To further increase awareness of this important public health issue and to identify states with potentially higher pregnancy-related crash risks,
Acknowledgments
CV received partial support from grant T32-HD052468-03 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland. The authors would like to thank Larry Cook at the University of Utah for his assistance with the probabilistic linkage, Eric Rodgman and Carol Martell at the University of North Carolina Highway Safety Research Center for their help with crash data acquisition and preparation, and Matt Avery at the
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