A retrospective cohort study of seatbelt use and pregnancy outcome after a motor vehicle crash.

To determine the effect of seatbelt use on pregnancy outcome we conducted a population-based retrospective cohort study of pregnant women (20 weeks' gestation or more) involved in motor vehicle collisions. Birth and fetal death certificates were obtained for 1243 restrained and 1349 unrestrained pregnant women involved in police-investigated motor vehicle crashes from 1980 through 1988. Unrestrained pregnant women drivers were 1.9 times more likely to have a low birth weight baby (95% confidence intervals = 1.2, 2.9) and 2.3 times more likely to give birth within 48 hours after the motor vehicle crash (95% confidence intervals = 1.1, 4.8) than restrained pregnant women drivers after adjusting for age and gestational age at crash. Although a trend for an increased risk of fetal deaths was observed among unrestrained women, too few fetal deaths occurred to accurately describe any association with restraint status. This study provides reassurance that the current recommendations on use of seatbelts by pregnant women are appropriate and should be continued.