Trauma complicates 6% to 7% of all pregnancies. Adverse outcomes are rare when monitoring is normal and early warning signs absent. Trauma systems often use pregnancy as the sole criterion (PSC) for partial trauma team activation. This study compares outcomes of pregnant patients presenting with PSC versus other physiologic, mechanistic, or anatomic (OPMA) activation criteria. Three hundred fifty-two consecutive obstetric partial trauma team activation patients (2000-2005) were grouped by length of gestation and evaluated for activation criteria and early maternal and fetal outcomes. Data were analyzed using descriptive statistics and analysis of variance. Patients ranged in age from 16 to 44 (mean age, 28 ± 6.4) and in weeks gestation between 1 and 40 weeks (mean, 25 ± 8 weeks). Eighty-two percent had been in vehicle crashes. One hundred eighty-eight (58%) were activated based on PSC and 137 on OPMA. No PSC patient had injuries sufficient to warrant trauma service admission. Ninety-four percent of all PSCs of <20 weeks were discharged home from the emergency department. There were no maternal mortalities. There were four fetal mortalities; two pregnancies were terminally compromised before the trauma event. No patient in the PSC group required admission to the trauma service. There were seven cases of abruption (2%) and 18 cases of vaginal bleeding or discharge (6%). No case of vaginal bleeding or abruption in the first 20 weeks was hypotensive at the scene or on arrival. In this study, pregnancy was not an independent predictor of the need for trauma team activation. St and ard OPMA trauma activation criteria apply equally to pregnant and nonpregnant patients. These data provide support for more judicious allocation of scarce trauma systems resources. © 2007 Lippincott Williams and Wilkins, Inc.