The relationship between maternal age and uterine dysfunction: a continuous effect throughout reproductive life.

OBJECTIVE In a selected low-risk population with spontaneous term labor we sought to determine whether there was a continuous effect of maternal age on uterine function. STUDY DESIGN With our comprehensive computerized database and medical record system, we identified 8496 patients who were nulliparous and in spontaneous labor at term (> or =37 weeks' gestation) with singleton fetuses in vertex presentation. This group was then analyzed according to maternal age for measures of labor dysfunction and rates of operative delivery. Analysis of variance and chi(2) statistics were used. RESULTS Use of oxytocin, duration of second stage of labor, cesarean delivery, cesarean delivery for failure to progress, and operative vaginal delivery rates were significantly increased with advancing maternal age (P <.0001). These increases appeared to be continuous functions beginning during the early 20s rather than new phenomena beginning after age 35 years. CONCLUSION Among nulliparous patients with uncomplicated labor there is a continuously increasing risk of uterine dysfunction related to maternal age.