PROVIDENCE, R.I. – Compared with cesarean birth without labor, undergoing vaginal birth increased the risk of stress incontinence and prolapse in women who were examined 5-10 years after childbirth, Dr. Victoria L. Handa reported at the annual meeting of the American Urogynecologic Society.
The risk of all pelvic disorders, including prolapse, was elevated even further in women who had undergone operative vaginal delivery, she said.
"The results suggest no measurable differences in the relative odds of any pelvic floor disorder for women delivering by cesarean section, including those who labored into the second stage. For vaginal birth, the picture is very different," said Dr. Handa, director of the advanced training program in female pelvic medicine and reconstructive surgery at Johns Hopkins University, Baltimore.
In this longitudinal cohort study based on hospital obstetric records, 8,285 women who had their first child 5-10 years previously were recruited for the study and 1,011 were enrolled. Women were selected if their obstetric history met one of five categories: cesarean without labor (considered the reference group; n = 192), cesarean during active labor (n = 228), cesarean after complete cervical dilation (n = 140), spontaneous vaginal birth (n = 325), and operative vaginal birth (n = 126). Groups were matched for age at first delivery and interval from first delivery, and were similar with respect to parity and smoking status. At enrollment, a validated questionnaire (Epidemiology of Prolapse and Incontinence Questionnaire) was used to assess pelvic floor symptoms, and the women were examined for pelvic organ support using the Pelvic Organ Prolapse Quantification (POP-Q) System.
"One of the strengths of our study is that [obstetric] exposures were verified by chart review with validated outcomes, and there was [anatomical] evidence of prolapse," Dr. Handa said.
Overall, 11% of the 1,011 women had stress urinary incontinence, 8% had overactive bladder, and 11% had anal incontinence; 3% reported prolapse symptoms, and 7% had prolapse upon examination (Obstet. Gynecol. 2011;118:777-84).
When the group was analyzed according to obstetric history, the impact of vaginal birth emerged. Compared with women who had a cesarean birth before active labor, women who had a vaginal birth (but no operative vaginal births) had almost a threefold increased risk of stress incontinence and symptomatic prolapse. The odds ratio for prolapse to or beyond the hymen was increased more than fivefold.
Women who had undergone operative vaginal birth fared even worse. The adjusted odds of stress incontinence and overactive bladder were more than quadrupled and the odds of anal incontinence were doubled. There was almost an eightfold increased risk of prolapse to or beyond the hymen upon examination.
In her report, Dr. Handa noted that in addition to demonstrating the dramatic increase in pelvic floor disorders in women with a history of at least one operative vaginal birth, the results showed an increase in urinary incontinence after operative delivery – a finding that had not been definitively documented before. For those who had undergone cesarean delivery, the results showed no association between active labor and pelvic floor disorders.
Consider the Big Picture
The article by Dr. Handa and colleagues "provides further evidence that, relative to cesarean delivery, vaginal delivery continues to increase the risk for urinary incontinence remote from delivery in middle-aged and younger women," said Dr. Ingrid Nygaard. The study "is particularly important because it adds objective data to the paucity of literature about pelvic organ support after childbirth."
Dr. Nygaard noted that one dilemma in conducting research about pelvic organ prolapse is the lag between the primary insult (childbirth) and the onset of pelvic floor disorders. She said that the study results are consistent with data from another recently published study that found a ninefold increase in surgery for pelvic organ prolapse in women 25 years after first delivery (Am. J. Obstet. Gynecol. 2011;204:70.e1-7).
She did say that "urogynecologists bear little if any responsibility for the dramatic rise in cesarean deliveries over the past couple of decades," and few cesarean deliveries in the United States currently are performed for pelvic floor protection. "However, requests for this, unheard of one generation ago, are increasing and no longer uncommon."
Dr. Nygaard did raise the question whether Dr. Handa’s findings are yet "another strike against vaginal delivery," with the "implied accusation that urogynecologists are working hard" to make vaginal deliveries extinct. But, she added, most women deliver vaginally, and most women do not have surgery for pelvic floor disorders. Cesarean delivery decreases the risk of pelvic floor disorders, but is not completely preventive, she said.
Despite witnessing "the ravages of vaginal birth," Dr. Nygaard said that she is not in favor of prioritizing pelvic floor disorders above other neonatal and maternal outcomes related to childbirth. "Until we have a better understanding of the big picture from a societal perspective," routinely advocating cesarean delivery to decrease pelvic floor disorders is ill advised, she concluded.
Dr. Nygaard is a urogynecologist at the University of Utah, Salt Lake City. Her comments were adapted from an editorial accompanying Dr. Handa’s article (Obstet. Gynecol. 2011;118:774-6). She reported that she had no conflicts of interest to disclose.
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