Objective: The purpose of this study was to assess the influence of maternal age on obstetric indices of uterine efficiency in spontaneous nulliparous labor managed according to a standardized protocol in order to determine whether increasing maternal age is more commonly associated with dystocia.
Study design: Information was collected prospectively and retrieved retrospectively from an obstetric database for a 5-year period on a consecutive series of nulliparas in spontaneous term (> or = 37 weeks' gestation) labor with singleton cephalic presentations. All women were managed according to an established Active Management protocol. Indices for dystocia, including need for oxytocin augmentation, prolonged labor (> 12 hr), instrumental delivery, and cesarean section were compared between 5 maternal age categories (< 20 years, 20-24, 25-29, 30-34, and > or = 35 years).
Results: The obstetric outcomes of 10,737 consecutive nulliparas in spontaneous term labor were analyzed for the 5 years 1998 to 2002. The incidences of oxytocin augmentation, prolonged labor, instrumental delivery, and intrapartum cesarean section including cesareans for dystocia all increased significantly and progressively with increasing maternal age. Mean gestational age and birth weight were similar in each age category.
Conclusion: In a context of uniform labor management, all 4 indices of dystocia examined were increased progressively with maternal age, although oxytocin augmentation proved a generally effective intervention in all age categories. These findings have implications for the analysis of intervention rates by health care providers, particularly in developed countries where the proportion of older nulliparas is increasing.