Objective: To measure the length of active labor (first and second stages) in a low-risk population of non-Hispanic white, Hispanic, and American Indian women, and to identify any differences among these ethnic populations.
Methods: Descriptive statistics are presented for 1473 low-risk women at term who delivered at the University of New Mexico Hospital. Data examined by ethnicity included demographics, intrapartum care and complications, and duration of the active-phase first stage (4 cm to complete cervical dilatation) and second stage (complete cervical dilatation to delivery) of labor.
Results: Compared with Friedman's criteria, 20% of these low-risk women had a prolonged active phase of the first stage, and 4% had a prolonged second stage, without excess maternal or infant morbidity. The mean length of active-phase, first-stage labor was 7.7 hours for nulliparas and 5.7 hours for multiparas (statistical limits 19.4 and 13.7 hours, respectively), with no differences according to ethnic group. The mean length of second stage was 53 minutes for nulliparas and 17 minutes for multiparas (statistical limits 147 and 57 minutes, respectively). American Indian nulliparas had significantly shorter second stages than non-Hispanic white women (P < .05).
Conclusion: Active labor in healthy women lasted longer than is widely appreciated. Upward revision of clinical expectations for the length of active labor is warranted.