BACKGROUND: The rate of incidental pregnancy in trauma patients and the incidence of associated fetal mortality, to our knowledge, have not been previously reported. The early diagnosis of pregnancy in trauma patients has become even more difficult because rapid pregnancy screens have been eliminated because of quality control issues. We determined the rate of incidental pregnancy and the sequelae of delayed diagnosis, including fetal radiation exposure and mortality. STUDY DESIGN: Data were analyzed retrospectively on all patients in whom pregnancy was diagnosed during a trauma admission during a 4-year period (1995 to 1999). Pregnancy was confirmed by β-HCG testing and gestational age estimated by an obstetrician by ultrasonography. Pregnancy outcomes were determined by a prospective telephone survey. RESULTS: One hundred fourteen (2.9%) of the 3,976 women (age 15 to 40 years) admitted to the trauma center were found to be pregnant. Thirteen (11.0%) were incidental pregnancies, of which 9 (8.0%) were newly diagnosed. Mean gestational age was significantly lower in the newly diagnosed pregnancies (6.9 versus 20.5 weeks, p<0.0005). Fetal mortality in this group was significantly higher (100% versus 25%, p<0.0005). The mean initial radiation exposure of all patients was 4.5 rads. Cumulative radiation exposure exceeded 5 rads in 85% of patients. CONCLUSIONS: Trauma patients diagnosed with incidental pregnancy are routinely exposed to doses of radiation exceeding the recommendations of the American College of Obstetrics and Gynecologists. Reinstitution of the rapid pregnancy test should be considered in all female trauma victims of childbearing age. This may promote a reduction in fetal radiation exposure and perhaps influence a portion of the fetal mortality in those patients with newly diagnosed incidental pregnancy.