The recent paper by Gyhagen et al. offers useful additional insight regarding the association between mode of delivery and urinary incontinence, especially in the long-term. Our concern, however, relates to some aspects of the data collection and analysis in the study in addition to the potentially misleading conclusion and inference that can be drawn from the paper.
It is well established that injury to the pelvic floor occurring as a result of vaginal birth is the single most common causal factor in the aetiology of stress urinary incontinence. The aetiology of urge urinary incontinence on the other hand is less well understood and usually not linked to childbirth. This paper did not explore the types of urinary incontinence developed by the women in this study. The result from the study therefore gives the impression that the excess urinary incontinence in the cohort of women who had a vaginal birth is all as a result of pelvic floor injury from vaginal birth. This is an oversimplification of the evidence as women who developed urge incontinence were not adjusted for in the data analysis. As the authors have not distinguished between the various types of urinary incontinence in their study, it is impossible to attribute the difference in urinary incontinence between the two arms of the study only to the effect of vaginal birth on the pelvic floor. We believe that a more informative result would have been generated if the focus of the study had either been on stress urinary incontinence or if women with urge urinary incontinence had been excluded or adjusted for in the data analysis.
The authors explored the relationship between mode of delivery and the severity of urinary incontinence development but they did not publish any data relating to this aspect of their study. Though urinary incontinence is common, it is the development of bothersome or clinically significant urinary incontinence that is pertinent. Evidence from a comparable study suggests that vaginal birth is more likely to result in bothersome or clinically significant urinary incontinence than caesarean section. More insight into the long-term validity of this information would be gained if the authors could release data in relation to this aspect of their study.
One of the conclusions drawn by the authors from their study is that the incident of urinary incontinence is the same among women who had caesarean section regardless of the timing of the caesarean section. The authors have not supported this -conclusion with data because they did not compare urinary incontinence outcome between the subsets of women who had caesarean section before or during the second stage of labour.
We would be appreciative if the authors could respond to these concerns.
Disclosure of interests
None to declare.