Objective: To investigate factors that contribute to the increased risk of cesarean delivery with advancing maternal age.
Study design: We reviewed demographic and ante- and intrapartum variables from a data set of term, nulliparous women who delivered at Brigham and Women's Hospital in 1998 (n = 3715).
Results: Cesarean delivery rates increased with advancing maternal age (< 25 years, 11.6%; > or = 40 years, 43.1%). Older women were more likely to have cesarean delivery without labor (< 25 years, 3.6%; > or = 40 years, 21.1%). Malpresentation and prior myomectomy were the indications for cesarean delivery without labor that were more prevalent in our older population as compared to our younger population. Even among women with spontaneous or induced labor, cesarean delivery rates increased with maternal age (< 25 years, 8.3%; > or = 40 years, 30.6%). Cesarean delivery rates were higher with induced labor, and rates of induction rose directly and continuously with maternal age, especially the rate of elective induction. Cesarean delivery for failure to progress or fetal distress was more common among older parturients, regardless of whether labor was spontaneous or induced. Among women who underwent cesarean delivery because of failure to progress, use of oxytocin and length of labor did not vary with age.
Conclusions: Older women are at higher risk for cesarean delivery in part because they are more likely to have cesarean delivery without labor. However, even among those women who labor, older women are more likely to undergo cesarean delivery, regardless of whether labor is spontaneous or induced. Part of the higher rate among older women who labor is explained by a higher rate of induction, particularly elective induction. Among women in both spontaneous and induced labor, cesarean delivery for the diagnoses of failure to progress and fetal distress was more frequent in older patients, although management of labor dystocia for these patients was similar to that for younger patients.