Vaginal birth linked to urinary incontinence
MedWire News: Vaginal birth is associated with an increased risk for urinary incontinence (UI) compared with a cesarean section, even over a decade afterwards, say researchers.
There was no difference in the prevalence of UI between women who underwent acute or elective cesarean section, indicating that the increased risk for UI is related to the later stages of delivery, when the fetus passes through the pelvic floor, say Ian Milsom (Sahlgrenska University Hospital, Gothenburg, Sweden) and co-authors.
They investigated the prevalence of and risk factors for UI 20 years after one vaginal delivery or cesarean section in 6148 women who gave birth for the first time between 1985 and 1988.
All women completed a 31-item postal questionnaire that included questions about current height and weight, urinary or anal incontinence and genital prolapse, menstrual status, hysterectomy, the menopause, and hormone treatment.
UI was defined according to the International Continence Society by the question "Do you have involuntary loss of urine?" Participants who experienced UI were grouped according to the duration of UI: <5 years, 5-10 years, or >10 years.
The findings showed that UI was 67% relatively more common after vaginal birth (40.3%) than after a cesarean (28.8%).
Based on the prevalence data available on UI, the authors used the number needed to treat principle to calculate that it would be necessary to perform eight or nine cesarean sections to avoid one case of UI.
The risk for UI persisting for more than 10 years almost trebled for vaginal birth compared with casarean section. Indeed, the prevalence of UI more than 10 years after vaginal birth was 10.1% versus 3.9% after cesarean birth.
However, there were no significant differences in the prevalence of UI between women who underwent acute cesarean section (performed during labor) compared with those who underwent an elective cesarean (before labor onset).
The increased prevalence of UI associated with vaginal birth was greater with each step up in body mass index (BMI) class (<25, 25-29.9, ≥ 30 kg/m2), indicating that "weight control is an important prophylactic measure to reduce UI," say the authors.
Furthermore, logistic regression analyses showed an 8% increased risk for UI per BMI unit increase, which was apparent for both modes of delivery.
The authors emphasize that their findings need to be considered in the wider context when weighing up the comparative benefits and risks of vaginal and cesarean delivery.
"Vaginal delivery and BMI have been shown to be important risk factors for UI, but operative delivery by caesarean section also involves a degree of risk for morbidity and mortality over and above that of vaginal delivery," Milsom et al conclude in the British Journal of Obstetrics and Gynecology.
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By Piriya Mahendra