NEW YORK (Reuters Health) - Compared with nulliparous women, women who deliver by cesarean section are at increased risk of urinary incontinence, according to a report in the March 6th issue of The New England Journal of Medicine. However, women who deliver vaginally are even more likely to develop this complication.

These findings shed light on risk factors for urinary incontinence, but they should not be used to justify increased use of c-section, lead author Dr. Guri Rortveit, from the University of Bergen in Norway, and colleagues note. Still, the results could be relevant to policy decisions regarding indications for cesarean delivery, the authors point out.

The study involved 15,307 adult women who were living in Norway between 1995 and 1997. Of these women, 3339 were nulliparous, 669 had delivered by c-section, and 11,299 had delivered vaginally.

After adjusting for age, the prevalence of incontinence in the nulliparous group was 10.1%, compared with 15.9% in the c-section group and 21% in the vaginal-delivery group, the investigators note. Considering only cases of moderate or severe incontinence, the corresponding rates were 3.7%, 6.2%, and 8.7%, respectively.

Stress and mixed-type incontinence were more common in the vaginal-delivery group than in the other groups. In contrast, urge incontinence was slightly more common in the c-section group than in the other groups.

Compared with nulliparous women, women who delivered by c-section were 40% more likely to develop moderate or severe incontinence, the authors note. Moreover, women who delivered vaginally were 2.2 times more likely than women who delivered by c-section to develop such incontinence.

"These results suggest that the mechanical strain during labor may add to the [urinary incontinence] risk associated with pregnancy itself," the investigators state.

In a related editorial, Dr. Howard Minkoff, from Maimonides Medical Center in New York, and Dr. Frank A. Chervanak, from New York Presbyterian Hospital, comment that the current findings suggest that "prophylactic cesarean delivery might reduce a woman's risk of moderate or severe urinary incontinence from 10% to 5%."

However, the applicability of these results to other populations is unclear, the editorialists note. The c-section rate in this Norwegian group of women was relatively low by US standards, they add.

N Engl J Med 2003;348:900-907,946-950.

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